Gentoo Linux Alpha HandbookContent:
A. Installing Gentoo1. About the Gentoo Linux InstallationFirst of all, welcome to Gentoo. You are about to enter the world of choices and performance. Gentoo is all about choices. When installing Gentoo, this is made clear to you several times -- you can choose how much you want to compile yourself, how to install Gentoo, what system logger you want, etc. Gentoo is a fast, modern metadistribution with a clean and flexible design. Gentoo is built around free software and doesn't hide from its users what is beneath the hood. Portage, the package maintenance system which Gentoo uses, is written in Python, meaning you can easily view and modify the source code. Gentoo's packaging system uses source code (although support for precompiled packages is included too) and configuring Gentoo happens through regular textfiles. In other words, openness everywhere. It is very important that you understand that choices are what makes Gentoo run. We try not to force you onto anything you don't like. If you feel like we do, please bugreport it. How is the Installation Structured? The Gentoo Installation can be seen as a 10-step procedure, corresponding to chapters 2 - 11. Every step results in a certain state:
When you are given a certain choice, we try our best to explain what the pros and cons are. We will continue then with a default choice, identified by "Default: " in the title. The other possibilities are marked by "Alternative: ". Do not think that the default is what we recommend. It is however what we believe most users will use. Sometimes you can pursue an optional step. Such steps are marked as "Optional: " and are therefore not needed to install Gentoo. However, some optional steps are dependent on a previous decision you made. We will inform you when this happens, both when you make the decision, and right before the optional step is described. You can install Gentoo in many different ways. You can download and install from one of our Installation CDs, from a distribution already installed, from a non-Gentoo bootable CD (such as Knoppix), from a netbooted environment, from a rescue floppy, etc. This document covers the installation using a Gentoo Installation CD or, in certain cases, netbooting. This installation assumes that you want to install the latest available version of each package.
If you want to perform a networkless installation, you should read the Gentoo 2008.0 Handbooks which contain the installation instructions for a networkless environment. Also note that, if you plan on using GRP (the Gentoo Reference Platform, a collection of prebuilt packages meant for immediate use after a Gentoo installation), you must follow the instructions in the Gentoo 2008.0 Handbooks. We also provide a Gentoo Installation Tips & Tricks document that might be useful to read as well. If you are an experienced Gentoo user and just need a brief installation checklist, feel free to use our Quick Installation Guide available from our Documentation Resources if your architecture has such a document available. You also have several possibilities: you can compile your entire system from scratch or use a prebuilt environment to have your Gentoo environment up and running in no time. And of course you have intermediate solutions in which you don't compile everything but start from a semi-ready system. If you find a problem in the installation (or in the installation documentation), please visit our bugtracking system and check if the bug is known. If not, please create a bugreport for it so we can take care of it. Do not be afraid of the developers who are assigned to (your) bugs -- they generally don't eat people. Note though that, although the document you are now reading is architecture-specific, it will contain references to other architectures as well. This is due to the fact that large parts of the Gentoo Handbook use source code that is common for all architectures (to avoid duplication of efforts and starvation of development resources). We will try to keep this to a minimum to avoid confusion. If you are uncertain if the problem is a user-problem (some error you made despite having read the documentation carefully) or a software-problem (some error we made despite having tested the installation/documentation carefully) you are free to join #gentoo on irc.freenode.net. Of course, you are welcome otherwise too as our chat channel covers the broad Gentoo spectrum :) Speaking of which, if you have a question regarding Gentoo, check out our Frequently Asked Questions, available from the Gentoo Documentation. You can also view the FAQs on our forums. 2. Choosing the Right Installation MediumBefore we start, we first list what hardware requirements you need to successfully install Gentoo on your box.
2.b. The Gentoo Installation CD The Gentoo Installation CDs are bootable CDs which contain a self-sustained Gentoo environment. They allow you to boot Linux from the CD. During the boot process your hardware is detected and the appropriate drivers are loaded. They are maintained by Gentoo developers. All Installation CDs allow you to boot, set up networking, initialize your partitions and start installing Gentoo from the Internet. Gentoo Minimal Installation CD The Minimal Installation CD is called install-alpha-minimal-<release>.iso and takes up around 110 MB of diskspace. You can use this Installation CD to install Gentoo, but only with a working Internet connection. A stage3 tarball is an archive containing a minimal Gentoo environment, suitable to continue the Gentoo installation using the instructions in this manual. Previously, the Gentoo Handbook described the installation using one of three stage tarballs. While Gentoo still offers stage1 and stage2 tarballs, the official installation method uses the stage3 tarball. If you are interested in performing a Gentoo installation using a stage1 or stage2 tarball, please read the Gentoo FAQ on How do I Install Gentoo Using a Stage1 or Stage2 Tarball? Stage3 tarballs can be downloaded from releases/alpha/autobuilds/current-stage3/ on any of the Official Gentoo Mirrors and are not provided on the LiveCD. 2.c. Download, Burn and Boot a Gentoo Installation CD Downloading and Burning the Installation CDs You have chosen to use a Gentoo Installation CD. We'll first start by downloading and burning the chosen Installation CD. We previously discussed the several available Installation CDs, but where can you find them? You can download any of the Installation CDs from one of our mirrors. The Installation CDs are located in the releases/alpha/autobuilds/current-iso/ directory. Inside that directory you'll find ISO files. Those are full CD images which you can write on a CD-R. In case you wonder if your downloaded file is corrupted or not, you can check its SHA-2 checksum and compare it with the SHA-2 checksum we provide (such as install-alpha-minimal-<release>.iso.DIGESTS). You can check the SHA-2 checksum with the sha512sum tool under Linux/Unix or File Checksum Tool for Windows. Another way to check the validity of the downloaded file is to use GnuPG to verify the cryptographic signature that we provide (the file ending with .asc). Download the signature file and obtain the public keys whose key ids can be found on the release engineering project site.
Now verify the signature:
To burn the downloaded ISO(s), you have to select raw-burning. How you do this is highly program-dependent. We will discuss cdrecord and K3B here; more information can be found in our Gentoo FAQ.
When your Alpha is powered on, the first thing that gets started is the firmware. It is loosely synonymous with the BIOS software on PC systems. There are two types of firmware on Alpha systems: SRM (Systems Reference Manual) and ARC (Advanced Risc Console). SRM is based on the Alpha Console Subsystem specification, which provides an operating environment for OpenVMS, Tru64 UNIX, and Linux operating systems. ARC is based on the Advanced RISC Computing (ARC) specification, which provides an operating environment for Windows NT. You can find a detailed guide on using SRM over at the Alpha Linux website. If your Alpha system supports both SRM and ARCs (ARC, AlphaBIOS, ARCSBIOS) you should follow these instructions for switching to SRM. If your system already uses SRM, you are all set. If your system can only use ARCs (Ruffian, nautilus, xl, etc.) you will need to choose MILO later on when we are talking about bootloaders. Now to boot an Alpha Installation CD, put the CD-ROM in the tray and reboot the system. You can use SRM to boot the Installation CD. If you cannot do that, you will have to use MILO.
You should have a root ("#") prompt on the current console and can also switch to other consoles by pressing Alt-F2, Alt-F3 and Alt-F4. Get back to the one you started on by pressing Alt-F1. Now continue with Extra Hardware Configuration. When the Installation CD boots, it tries to detect all your hardware devices and loads the appropriate kernel modules to support your hardware. In the vast majority of cases, it does a very good job. However, in some cases it may not auto-load the kernel modules you need. If the PCI auto-detection missed some of your system's hardware, you will have to load the appropriate kernel modules manually. In the next example we try to load the 8139too module (support for certain kinds of network interfaces):
If you plan on giving other people access to your installation environment or you want to chat using irssi without root privileges (for security reasons), you need to create the necessary user accounts and change the root password. To change the root password, use the passwd utility:
To create a user account, we first enter their credentials, followed by its password. We use useradd and passwd for these tasks. In the next example, we create a user called "john".
You can change your user id from root to the newly created user by using su:
Optional: Viewing Documentation while Installing If you want to view the Gentoo Handbook during the installation, make sure you have created a user account (see Optional: User Accounts). Then press Alt-F2 to go to a new terminal. You can view the handbook using links, once you have completed the Configuring your Network chapter (otherwise you won't be able to go on the Internet to view the document):
You can go back to your original terminal by pressing Alt-F1. Optional: Starting the SSH Daemon If you want to allow other users to access your computer during the Gentoo installation (perhaps because those users are going to help you install Gentoo, or even do it for you), you need to create a user account for them and perhaps even provide them with your root password (only do that if you fully trust that user). To fire up the SSH daemon, execute the following command:
To be able to use sshd, you first need to set up your networking. Continue with the chapter on Configuring your Network. 3. Configuring your Network3.a. Automatic Network Detection If your system is plugged into an Ethernet network with a DHCP server, it is very likely that your networking configuration has already been set up automatically for you. If so, you should be able to take advantage of the many included network-aware commands on the Installation CD such as ssh, scp, ping, irssi, wget and links, among others. If networking has been configured for you, the ifconfig command should list some network interfaces besides lo, such as eth0:
The interface name on your system can be quite different from eth0. Recent installation media might show regular network interfaces names like eno0, ens1 or enp5s0. Just seek the interface in the ifconfig output that has an IP address related to your local network. In the remainder of this document, we will assume that the interface is called eth0. Optional: Configure any Proxies If you access the Internet through a proxy, you might need to set up proxy information during the installation. It is very easy to define a proxy: you just need to define a variable which contains the proxy server information. In most cases, you can just define the variables using the server hostname. As an example, we assume the proxy is called proxy.gentoo.org and the port is 8080.
If your proxy requires a username and password, you should use the following syntax for the variable:
You may want to try pinging your ISP's DNS server (found in /etc/resolv.conf) and a Web site of your choice, just to make sure that your packets are reaching the net, DNS name resolution is working correctly, etc.
If you are now able to use your network, you can skip the rest of this section and continue with Preparing the Disks. If not, read on. 3.b. Automatic Network Configuration If the network doesn't work immediately, some installation media allow you to use net-setup (for regular or wireless networks), pppoe-setup (for ADSL-users) or pptp (for PPTP-users - available on x86, amd64, alpha, ppc and ppc64). If your installation medium does not contain any of these tools or your network doesn't function yet, continue with Manual Network Configuration.
The simplest way to set up networking if it didn't get configured automatically is to run the net-setup script:
net-setup will ask you some questions about your network environment. When all is done, you should have a working network connection. Test your network connection as stated before. If the tests are positive, congratulations! You are now ready to install Gentoo. Skip the rest of this section and continue with Preparing the Disks. If your network still doesn't work, continue with Manual Network Configuration. Assuming you need PPPoE to connect to the internet, the Installation CD (any version) has made things easy for you by including ppp. Use the provided pppoe-setup script to configure your connection. You will be prompted for the ethernet device that is connected to your adsl modem, your username and password, the IPs of your DNS servers and if you need a basic firewall or not.
If something goes wrong, double-check that you correctly typed your username and password by looking at /etc/ppp/pap-secrets or /etc/ppp/chap-secrets and make sure you are using the right ethernet device. If your ethernet device doesn't exist, you will have to load the appropriate network modules. In that case you should continue with Manual Network Configuration as we explain how to load the appropriate network modules there. If everything worked, continue with Preparing the Disks. If you need PPTP support, you can use pptpclient which is provided by our Installation CDs. But first you need to make sure that your configuration is correct. Edit /etc/ppp/pap-secrets or /etc/ppp/chap-secrets so it contains the correct username/password combination:
Then adjust /etc/ppp/options.pptp if necessary:
When all that is done, just run pptp (along with the options you couldn't set in options.pptp) to connect the server:
Now continue with Preparing the Disks. 3.c. Manual Network Configuration Loading the Appropriate Network Modules When the Installation CD boots, it tries to detect all your hardware devices and loads the appropriate kernel modules (drivers) to support your hardware. In the vast majority of cases, it does a very good job. However, in some cases, it may not auto-load the kernel modules you need. If net-setup or pppoe-setup failed, then it is possible that your network card wasn't found immediately. This means you may have to load the appropriate kernel modules manually. To find out what kernel modules we provide for networking, use ls:
If you find a driver for your network card, use modprobe to load the kernel module:
To check if your network card is now detected, use ifconfig. A detected network card would result in something like this (again, eth0 here is just an example):
If however you receive the following error, the network card is not detected:
The available network interface names on your system can be listed through the /sys file system:
In the above example, 6 interfaces are found. The eth0 one is most likely the (wired) Ethernet adapter whereas wlan0 is the wireless one. Assuming that you now have a detected network card, you can retry net-setup or pppoe-setup again (which should work now), but for the hardcore people amongst you we explain how to configure your network manually. Select one of the following sections based on your network setup:
DHCP (Dynamic Host Configuration Protocol) makes it possible to automatically receive networking information (IP address, netmask, broadcast address, gateway, nameservers etc.). This only works if you have a DHCP server in your network (or if your provider provides a DHCP service). To have a network interface receive this information automatically, use dhcpcd:
If this works (try pinging some internet server, like Google), then you are all set and ready to continue. Skip the rest of this section and continue with Preparing the Disks.
If you are using a wireless (802.11) card, you may need to configure your wireless settings before going any further. To see the current wireless settings on your card, you can use iwconfig. Running iwconfig might show something like:
For most users, there are only two settings that might be important to change, the ESSID (aka wireless network name) or the WEP key. If the ESSID and Access Point address listed are already that of your access point and you are not using WEP, then your wireless is working. If you need to change your ESSID, or add a WEP key, you can issue the following commands:
You can then confirm your wireless settings again by using iwconfig. Once you have wireless working, you can continue configuring the IP level networking options as described in the next section (Understanding Network Terminology) or use the net-setup tool as described previously. Understanding Network Terminology
If all of the above fails, you will have to configure your network manually. This is not difficult at all. However, you need to be familiar with some network terminology, as you will need it to be able to configure your network to your satisfaction. After reading this, you will know what a gateway is, what a netmask serves for, how a broadcast address is formed and why you need nameservers. In a network, hosts are identified by their IP address (Internet Protocol address). Such an address is a combination of four numbers between 0 and 255. Well, at least that is how we perceive it. In reality, such an IP address consists of 32 bits (ones and zeros). Let's view an example:
Such an IP address is unique to a host as far as all accessible networks are concerned (i.e. every host that you are able to reach must have a unique IP address). In order to distinguish between hosts inside and outside a network, the IP address is divided in two parts: the network part and the host part. The separation is written down with the netmask, a collection of ones followed by a collection of zeros. The part of the IP that can be mapped on the ones is the network-part, the other one is the host-part. As usual, the netmask can be written down as an IP-address.
In other words, 192.168.0.14 is still part of our example network, but 192.168.1.2 is not. The broadcast address is an IP-address with the same network-part as your network, but with only ones as host-part. Every host on your network listens to this IP address. It is truly meant for broadcasting packets.
To be able to surf on the internet, you must know which host shares the Internet connection. This host is called the gateway. Since it is a regular host, it has a regular IP address (for instance 192.168.0.1). We previously stated that every host has its own IP address. To be able to reach this host by a name (instead of an IP address) you need a service that translates a name (such as dev.gentoo.org) to an IP address (such as 64.5.62.82). Such a service is called a name service. To use such a service, you must define the necessary name servers in /etc/resolv.conf. In some cases, your gateway also serves as nameserver. Otherwise you will have to enter the nameservers provided by your ISP. To summarise, you will need the following information before continuing:
Setting up your network consists of three steps. First we assign ourselves an IP address using ifconfig. Then we set up routing to the gateway using route. Then we finish up by placing the nameserver IPs in /etc/resolv.conf. To assign an IP address, you will need your IP address, broadcast address and netmask. Then execute the following command, substituting ${IP_ADDR} with your IP address, ${BROADCAST} with your broadcast address and ${NETMASK} with your netmask:
Now set up routing using route. Substitute ${GATEWAY} with your gateway IP address:
Now open /etc/resolv.conf with your favorite editor (in our example, we use nano):
Now fill in your nameserver(s) using the following as a template. Make sure you substitute ${NAMESERVER1} and ${NAMESERVER2} with the appropriate nameserver addresses:
That's it. Now test your network by pinging some Internet server (like Google). If this works, congratulations then. You are now ready to install Gentoo. Continue with Preparing the Disks. 4. Preparing the Disks4.a. Introduction to Block Devices We'll take a good look at disk-oriented aspects of Gentoo Linux and Linux in general, including Linux filesystems, partitions and block devices. Then, once you're familiar with the ins and outs of disks and filesystems, you'll be guided through the process of setting up partitions and filesystems for your Gentoo Linux installation. To begin, we'll introduce block devices. The most famous block device is probably the one that represents the first drive in a Linux system, namely /dev/sda. SCSI and Serial ATA drives are both labeled /dev/sd*; even IDE drives are labeled /dev/sd* with the new libata framework in the kernel. If you're using the old device framework, then your first IDE drive is /dev/hda. The block devices above represent an abstract interface to the disk. User programs can use these block devices to interact with your disk without worrying about whether your drives are IDE, SCSI or something else. The program can simply address the storage on the disk as a bunch of contiguous, randomly-accessible 512-byte blocks. Although it is theoretically possible to use a full disk to house your Linux system, this is almost never done in practice. Instead, full disk block devices are split up in smaller, more manageable block devices. On Alpha systems, these are called slices. 4.b. Designing a Partitioning Scheme As an example we use the following slice layout:
If you are interested in knowing how big a partition should be, or even how many partitions (or volumes) you need, read on. Otherwise continue now with Using fdisk to Partition your Disk (SRM only) or Using fdisk to Partition your Disk (ARC/AlphaBIOS only). The number of partitions is highly dependent on your environment. For instance, if you have lots of users, you will most likely want to have your /home separate as it increases security and makes backups easier. If you are installing Gentoo to perform as a mailserver, your /var should be separate as all mails are stored inside /var. A good choice of filesystem will then maximise your performance. Gameservers will have a separate /opt as most gaming servers are installed there. The reason is similar for /home: security and backups. You will definitely want to keep /usr big: not only will it contain the majority of applications, the Portage tree alone takes around 500 Mbyte excluding the various sources that are stored in it. As you can see, it very much depends on what you want to achieve. Separate partitions or volumes have the following advantages:
However, multiple partitions have disadvantages as well. If not configured properly, you will have a system with lots of free space on one partition and none on another. Another nuisance is that separate partitions - especially for important mountpoints like /usr or /var - often require the administrator to boot with an initramfs to mount the partition before other boot scripts start. This isn't always the case though, so your results may vary. 4.c. Using fdisk to Partition your Disk (SRM only) The following parts explain how to create the example slice layout described previously, namely:
Change your slice layout according to your own preference. To figure out what disks you have running, use the following commands:
From this output you should be able to see what disks were detected and their respective /dev entry. In the following parts we assume that the disk is a SCSI disk on /dev/sda. Now fire up fdisk:
If your hard drive is completely blank, then you'll have to first create a BSD disklabel.
We start with deleting all slices except the 'c'-slice (a requirement for using BSD disklabels). The following shows how to delete a slice (in the example we use 'a'). Repeat the process to delete all other slices (again, except the 'c'-slice). Use p to view all existing slices. d is used to delete a slice.
After repeating this process for all slices, a listing should show you something similar to this:
On Alpha based systems you don't need a separate boot slice. However, the first cylinder cannot be used as the aboot image will be placed there. We will create a swap slice starting at the third cylinder, with a total size of 1 GB. Use n to create a new slice. After creating the slice, we will change its type to 1 (one), meaning swap.
After these steps you should see a layout similar to the following:
We will now create the root slice, starting from the first cylinder after the swap slice. Use the p command to view where the swap slice ends. In our example, this is at 1003, making the root slice start at 1004. Another problem is that there is currently a bug in fdisk making it think the number of available cylinders is one above the real number of cylinders. In other words, when you are asked for the last cylinder, decrease the cylinder number (in this example: 5290) with one. When the slice is created, we change the type to 8, for ext2.
Your slice layout should now be similar to this:
Save the Slice Layout and Exit Save fdisk by typing w. This will also save your slice layout.
Now that your slices are created, you can continue with Creating Filesystems. 4.d. Using fdisk to Partition your Disk (ARC/AlphaBIOS only) The following parts explain how to partition the disk with a layout similar to the one described previously, namely:
Change your partition layout according to your own preference. To figure out what disks you have running, use the following commands:
From this output you should be able to see what disks were detected and their respective /dev entry. In the following parts we assume that the disk is a SCSI disk on /dev/sda. Now fire up fdisk:
If your hard drive is completely blank, then you'll have to first create a DOS disklabel.
We start with deleting all partitions. The following shows how to delete a partition (in the example we use '1'). Repeat the process to delete all other partitions. Use p to view all existing partitions. d is used to delete a partition.
On Alpha systems which use MILO to boot, we have to create a small vfat boot partition.
We will create a swap partition with a total size of 1 GB. Use n to create a new partition.
After these steps you should see a layout similar to the following:
We will now create the root partition. Again, just use the n command.
After these steps you should see a layout similar to the following:
Save the Partition Layout and Exit Save fdisk by typing w. This will also save your partition layout.
Now that your partitions are created, you can continue with Creating Filesystems. Now that your partitions are created, it is time to place a filesystem on them. If you don't care about what filesystem to choose and are happy with what we use as default in this handbook, continue with Applying a Filesystem to a Partition. Otherwise read on to learn about the available filesystems... The Linux kernel supports various filesystems. We'll explain ext2, ext3, ext4, ReiserFS, XFS and JFS as these are the most commonly used filesystems on Linux systems.
ext2 is the tried and true Linux filesystem but doesn't have metadata journaling, which means that routine ext2 filesystem checks at startup time can be quite time-consuming. There is now quite a selection of newer-generation journaled filesystems that can be checked for consistency very quickly and are thus generally preferred over their non-journaled counterparts. Journaled filesystems prevent long delays when you boot your system and your filesystem happens to be in an inconsistent state. If you intend to install Gentoo on a very small disk (less than 4GB), then you'll need to tell ext2 to reserve enough inodes when you create the filesystem. The mke2fs application uses the "bytes-per-inode" setting to calculate how many inodes a file system should have. By running mke2fs -T small /dev/<device> the number of inodes will generally quadruple for a given file system as its "bytes-per-inode" reduces from one every 16kB to one every 4kB. You can tune this even further by using mke2fs -i <ratio> /dev/<device>. ext3 is the journaled version of the ext2 filesystem, providing metadata journaling for fast recovery in addition to other enhanced journaling modes like full data and ordered data journaling. It uses an HTree index that enables high performance in almost all situations. In short, ext3 is a very good and reliable filesystem. If you intend to install Gentoo on a very small disk (less than 4GB), then you'll need to tell ext3 to reserve enough inodes when you create the filesystem. The mke2fs application uses the "bytes-per-inode" setting to calculate how many inodes a file system should have. By running mke2fs -j -T small /dev/<device> the number of inodes will generally quadruple for a given file system as its "bytes-per-inode" reduces from one every 16kB to one every 4kB. You can tune this even further by using mke2fs -j -i <ratio> /dev/<device>. ext4 is a filesystem created as a fork of ext3 bringing new features, performance improvements and removal of size limits with moderate changes to the on-disk format. It can span volumes up to 1 EB and with maximum file size of 16 TB. Instead of the classic ext2/3 bitmap block allocation ext4 uses extents, which improve large file performance and reduce fragmentation. Ext4 also provides more sophisticated block allocation algorithms (delayed allocation and multiblock allocation) giving the filesystem driver more ways to optimise the layout of data on the disk. The ext4 filesystem is a compromise between production-grade code stability and the desire to introduce extensions to an almost decade old filesystem. Ext4 is the recommended all-purpose all-platform filesystem. JFS is IBM's high-performance journaling filesystem. JFS is a light, fast and reliable B+tree-based filesystem with good performance in various conditions. ReiserFS is a B+tree-based journaled filesystem that has good overall performance, especially when dealing with many tiny files at the cost of more CPU cycles. ReiserFS appears to be less maintained than other filesystems. XFS is a filesystem with metadata journaling which comes with a robust feature-set and is optimized for scalability. XFS seems to be less forgiving to various hardware problems. Applying a Filesystem to a Partition To create a filesystem on a partition or volume, there are tools available for each possible filesystem:
For instance, to have the root partition (/dev/sda2 in our example) in ext4, you would use:
Now create the filesystems on your newly created partitions (or logical volumes). mkswap is the command that is used to initialize swap partitions:
To activate the swap partition, use swapon:
Create and activate the swap with the commands mentioned above. Now that your partitions are initialized and are housing a filesystem, it is time to mount those partitions. Use the mount command. Don't forget to create the necessary mount directories for every partition you created. As an example we mount the root partition:
We will also have to mount the proc filesystem (a virtual interface with the kernel) on /proc. But first we will need to place our files on the partitions. Continue with Installing the Gentoo Installation Files. 5. Installing the Gentoo Installation Files5.a. Installing a Stage Tarball Before you continue you need to check your date/time and update it. A misconfigured clock may lead to strange results in the future! To verify the current date/time, run date:
If the date/time displayed is wrong, update it using the date MMDDhhmmYYYY syntax (Month, Day, hour, minute and Year). At this stage, you should use UTC time. You will be able to define your timezone later on. For instance, to set the date to March 29th, 16:21 in the year 2005:
The next step you need to perform is to install the stage3 tarball onto your system. The command uname -m can be used to help you decide which stage file to download as it provides information on the architecture of your system. 5.b. Using a Stage from the Internet Go to the Gentoo mountpoint at which you mounted your filesystems (most likely /mnt/gentoo):
Depending on your installation medium, you have a couple of tools available to download a stage. If you have links available, then you can immediately surf to the Gentoo mirrorlist and choose a mirror close to you: type links http://www.gentoo.org/main/en/mirrors.xml and press enter. If you don't have links available you should have lynx at your disposal. If you need to go through a proxy, export the http_proxy and ftp_proxy variables:
We will now assume that you have links at your disposal. Select a mirror closeby. Usually HTTP mirrors suffice, but other protocols are available as well. Move to the releases/alpha/autobuilds/ directory. There you should see all available stage files for your architecture (they might be stored within subdirectories named after the individual subarchitectures). Select one and press D to download. When you're finished, press Q to quit the browser.
Make sure you download a stage3 tarball - installations using a stage1 or stage2 tarball are not supported anymore (and in most cases, you will not find stage1 or stage2 tarballs on our regular download mirrors anyway). If you want to check the integrity of the downloaded stage tarball, use openssl and compare the output with the checksums provided on the mirror. The digests files provide several checksums, each taken with a different algorithm. The recommended ones are SHA512 and Whirlpool.
Then compare the output of these commands with the value registered in the .DIGESTS files that can be found on the mirrors as well. The values need to match, otherwise the downloaded file might be corrupt (or the digests file is). Now unpack your downloaded stage onto your system. We use tar to proceed as it is the easiest method:
Make sure that you use the same options (xvjpf). The x stands for Extract, the v for Verbose to see what happens during the extraction process (optional), the j for Decompress with bzip2, the p for Preserve permissions and the f to denote that we want to extract a file, not standard input. Now that the stage is installed, continue with Configuring the Compile Options. 5.c. Configuring the Compile Options To optimize Gentoo, you can set a couple of variables which impact Portage behaviour. All those variables can be set as environment variables (using export) but that isn't permanent. To keep your settings, Portage provides you with /etc/portage/make.conf, a configuration file for Portage. It is this file we will edit now.
Fire up your favorite editor (in this guide we use nano) so we can alter the optimization variables we will discuss hereafter.
As you probably noticed, the make.conf.example file is structured in a generic way: commented lines start with "#", other lines define variables using the VARIABLE="content" syntax. The make.conf file uses the same syntax. Several of those variables are discussed next. The CFLAGS and CXXFLAGS variables define the optimization flags for the gcc C and C++ compiler respectively. Although we define those generally here, you will only have maximum performance if you optimize these flags for each program separately. The reason for this is because every program is different. In make.conf you should define the optimization flags you think will make your system the most responsive generally. Don't place experimental settings in this variable; too much optimization can make programs behave bad (crash, or even worse, malfunction). We will not explain all possible optimization options. If you want to know them all, read the GNU Online Manual(s) or the gcc info page (info gcc -- only works on a working Linux system). The make.conf.example file itself also contains lots of examples and information; don't forget to read it too. A first setting is the -march= or -mcpu= flag, which specifies the name of the target architecture. Possible options are described in the make.conf.example file (as comments). A commonly used value is native as that tells the compiler to select the target architecture of the current system (the one you are installing on). A second one is the -O flag (that is a capital O, not a zero), which specifies the gcc optimization class flag. Possible classes are s (for size-optimized), 0 (zero - for no optimizations), 1, 2 or even 3 for more speed-optimization flags (every class has the same flags as the one before, plus some extras). -O2 is the recommended default. -O3 is known to cause problems when used system-wide, so we recommend that you stick to -O2. Another popular optimization flag is -pipe (use pipes rather than temporary files for communication between the various stages of compilation). It has no impact on the generated code, but uses more memory. On systems with low memory, gcc might get killed. In that case, do not use this flag. Using -fomit-frame-pointer (which doesn't keep the frame pointer in a register for functions that don't need one) might have serious repercussions on the debugging of applications. When you define the CFLAGS and CXXFLAGS, you should combine several optimization flags. The default values contained in the stage3 archive you unpacked should be good enough. The following example is just an example:
With MAKEOPTS you define how many parallel compilations should occur when you install a package. A good choice is the number of CPUs (or CPU cores) in your system plus one, but this guideline isn't always perfect.
Update your /mnt/gentoo/etc/portage/make.conf to your own preference and save (nano users would hit Ctrl-X). You are now ready to continue with Installing the Gentoo Base System. 6. Installing the Gentoo Base SystemIn order to download source code quickly it is recommended to select a fast mirror. Portage will look in your make.conf file for the GENTOO_MIRRORS variable and use the mirrors listed therein. You can surf to our mirror list and search for a mirror (or mirrors) close to you (as those are most frequently the fastest ones), but we provide a nice tool called mirrorselect which provides you with a nice interface to select the mirrors you want. Just navigate to the mirrors of choice and press spacebar to select one or more mirrors.
A second important setting is the SYNC setting in make.conf. This variable contains the rsync server you want to use when updating your Portage tree (the collection of ebuilds, scripts containing all the information Portage needs to download and install software). Although you can manually enter a SYNC server for yourself, mirrorselect can ease that operation for you:
After running mirrorselect it is adviseable to double-check the settings in /mnt/gentoo/etc/portage/make.conf !
One thing still remains to be done before we enter the new environment and that is copying over the DNS information in /etc/resolv.conf. You need to do this to ensure that networking still works even after entering the new environment. /etc/resolv.conf contains the nameservers for your network.
Mounting the necessary Filesystems In a few moments, we will change the Linux root towards the new location. To make sure that the new environment works properly, we need to make certain file systems available there as well. Mount the /proc filesystem on /mnt/gentoo/proc to allow the installation to use the kernel-provided information within the chrooted environment, and then mount-bind the /dev and /sys filesystems.
Now that all partitions are initialized and the base environment installed, it is time to enter our new installation environment by chrooting into it. This means that we change from the current installation environment (Installation CD or other installation medium) to your installation system (namely the initialized partitions). This chrooting is done in three steps. First we will change the root from / (on the installation medium) to /mnt/gentoo (on your partitions) using chroot. Then we will reload some settings, as provided by /etc/profile, in memory using source. The last step is to redefine the primary prompt to help us remember that we are inside a chroot environment.
Congratulations! You are now inside your own Gentoo Linux environment. Of course it is far from finished, which is why the installation still has some sections left :-) If you at any time would need another terminal or console to access the chroot environment, all you need to do is to execute the above steps again. You now have to install a Portage snapshot, a collection of files that inform Portage what software titles you can install, which profiles are available, etc. The contents of this snapshot will be extracted to /usr/portage. We recommend the use of emerge-webrsync. This will fetch the latest portage snapshot (which Gentoo releases on a daily basis) from one of our mirrors and install it onto your system.
Optional: Updating the Portage tree You can now update your Portage tree to the latest version. emerge --sync will use the rsync protocol to update the Portage tree (which you fetched earlier on through emerge-webrsync) to the latest state.
If you are behind a firewall that blocks rsync traffic, you safely ignore this step as you already have a quite up-to-date Portage tree. If you are warned that a new Portage version is available and that you should update Portage, you should do it now using emerge --oneshot portage. You might also be notified that "news items need reading". More on that next. When a Portage tree is synchronized to your system, Portage might warn you with the following:
Portage news items were created to provide a communication medium to push critical messages to users via the rsync tree. To manage them you will need to use eselect news. With the read subcommand, you can read all news items. With list you can get an overview of the available news items, and with purge you can remove them once you have read them and have no further need for the item(s) anymore.
More information about the newsreader is available through its manual page: man news.eselect. First, a small definition is in place. A profile is a building block for any Gentoo system. Not only does it specify default values for USE, CFLAGS and other important variables, it also locks the system to a certain range of package versions. This is all maintained by the Gentoo developers. Previously, such a profile was untouched by the users. However, there may be certain situations in which you may decide a profile change is necessary. You can see what profile you are currently using with the following command:
As you can see, there are also desktop and server subprofiles available for some architectures. Running eselect profile list will show all available profiles. After viewing the available profiles for your architecture, you can use a different one if you wish:
USE is one of the most powerful variables Gentoo provides to its users. Several programs can be compiled with or without optional support for certain items. For instance, some programs can be compiled with gtk-support, or with qt-support. Others can be compiled with or without SSL support. Some programs can even be compiled with framebuffer support (svgalib) instead of X11 support (X-server). Most distributions compile their packages with support for as much as possible, increasing the size of the programs and startup time, not to mention an enormous amount of dependencies. With Gentoo you can define what options a package should be compiled with. This is where USE comes into play. In the USE variable you define keywords which are mapped onto compile-options. For instance, ssl will compile ssl-support in the programs that support it. -X will remove X-server support (note the minus sign in front). gnome gtk -kde -qt4 will compile your programs with gnome (and gtk) support, and not with kde (and qt) support, making your system fully tweaked for GNOME. The default USE settings are placed in the make.defaults files of your profile. You will find make.defaults files in the directory which /etc/portage/make.profile points to and all parent directories as well. The default USE setting is the sum of all USE settings in all make.defaults files. What you place in /etc/portage/make.conf is calculated against these defaults settings. If you add something to the USE setting, it is added to the default list. If you remove something from the USE setting (by placing a minus sign in front of it) it is removed from the default list (if it was in the default list at all). Never alter anything inside the /etc/portage/make.profile directory; it gets overwritten when you update Portage! A full description on USE can be found in the second part of the Gentoo Handbook, USE flags. A full description on the available USE flags can be found on your system in /usr/portage/profiles/use.desc.
As an example we show a USE setting for a KDE-based system with DVD, ALSA and CD Recording support:
Finally select your timezone so that your system knows where it is physically located. Look for your timezone in /usr/share/zoneinfo, then copy it to /etc/localtime. Please avoid the /usr/share/zoneinfo/Etc/GMT* timezones as their names do not indicate the expected zones. For instance, GMT-8 is in fact GMT+8.
7. Configuring the KernelThe core around which all distributions are built is the Linux kernel. It is the layer between the user programs and your system hardware. Gentoo provides its users several possible kernel sources. A full listing with description is available at the Gentoo Kernel Guide. For alpha-based systems we have gentoo-sources (the default 2.6 kernel source).
When you take a look in /usr/src you should see a symlink called linux pointing to your kernel source. In this case, the installed kernel source points to gentoo-sources-3.3.8. Your version may be different, so keep this in mind.
Now it is time to configure and compile your kernel source. You can use genkernel for this, which will build a generic kernel as used by the Installation CD. We explain the "manual" configuration first though, as it is the best way to optimize your environment. If you want to manually configure your kernel, continue now with Default: Manual Configuration. If you want to use genkernel you should read Alternative: Using genkernel instead. 7.b. Default: Manual Configuration Manually configuring a kernel is often seen as the most difficult procedure a Linux user ever has to perform. Nothing is less true -- after configuring a couple of kernels you don't even remember that it was difficult ;) However, one thing is true: you must know your system when you start configuring a kernel manually. Most information can be gathered by emerging pciutils (emerge pciutils) which contains lspci. You will now be able to use lspci within the chrooted environment. You may safely ignore any pcilib warnings (like pcilib: cannot open /sys/bus/pci/devices) that lspci throws out. Alternatively, you can run lspci from a non-chrooted environment. The results are the same. You can also run lsmod to see what kernel modules the Installation CD uses (it might provide you with a nice hint on what to enable). Now go to your kernel source directory and execute make menuconfig. This will fire up an ncurses-based configuration menu.
You will be greeted with several configuration sections. We'll first list some options you must activate (otherwise Gentoo will not function, or not function properly without additional tweaks). First go to File Systems and select support for the filesystems you use. Don't compile the file system you use for the root filesystem as module, otherwise your Gentoo system will not be able to mount your partition. Also select Virtual memory and /proc file system.
If you are using PPPoE to connect to the Internet or you are using a dial-up modem, you will need the following options in the kernel:
The two compression options won't harm but are not definitely needed, neither does the PPP over Ethernet option, that might only be used by ppp when configured to do kernel mode PPPoE. If you require it, don't forget to include support in the kernel for your ethernet card. The following options are recommended as well:
Next select Maintain a devtmpfs file system to mount at /dev so that critical device files are already available early in the boot process.
When you've finished configuring the kernel, continue with Compiling and Installing. Now that your kernel is configured, it is time to compile and install it. Exit the configuration and start the compilation process:
When the kernel has finished compiling, copy the kernel image to /boot. Recent kernels might create vmlinux instead of vmlinux.gz. Keep this in mind when you copy your kernel image.
(Optional) Building an Initramfs If you use a specific partition layout where important file system locations (like /usr or /var) are on separate partitions, then you will need to setup an initramfs so that this partition can be mounted before it is needed. Without an initramfs, you risk that the system will not boot up properly as the tools that are responsible for mounting the file systems need information that resides on those file systems. An initramfs will pull in the necessary files into an archive which is used right after the kernel boots, but before the control is handed over to the init tool. Scripts on the initramfs will then make sure that the partitions are properly mounted before the system continues booting. To install an initramfs, install genkernel first, then have it generate an initramfs for you.
If you need specific support in the initramfs, such as lvm or raid, add in the appropriate options to genkernel. See genkernel --help for more information, or the next example which enables support for LVM and software raid (mdadm):
The initramfs will be stored in /boot. You can find the file by simply listing the files starting with initramfs:
Now continue with Kernel Modules. 7.c. Alternative: Using genkernel If you are reading this section, you have chosen to use our genkernel script to configure your kernel for you. Now that your kernel source tree is installed, it's now time to compile your kernel by using our genkernel script to automatically build a kernel for you. genkernel works by configuring a kernel nearly identically to the way our Installation CD kernel is configured. This means that when you use genkernel to build your kernel, your system will generally detect all your hardware at boot-time, just like our Installation CD does. Because genkernel doesn't require any manual kernel configuration, it is an ideal solution for those users who may not be comfortable compiling their own kernels. Now, let's see how to use genkernel. First, emerge the genkernel ebuild:
Now, compile your kernel sources by running genkernel all. Be aware though, as genkernel compiles a kernel that supports almost all hardware, this compilation will take quite a while to finish! Note that, if your boot partition doesn't use ext2 or ext3 as filesystem you need to manually configure your kernel using genkernel --menuconfig all and add support for your filesystem in the kernel (i.e. not as a module).
Once genkernel completes, a kernel, full set of modules and initial ram disk (initramfs) will be created. We will use the kernel and initrd when configuring a boot loader later in this document. Write down the names of the kernel and initrd as you will need it when writing the bootloader configuration file. The initrd will be started immediately after booting to perform hardware autodetection (just like on the Installation CD) before your "real" system starts up.
You should list the modules you want automatically loaded in /etc/conf.d/modules. You can add extra options to the modules too if you want. To view all available modules, run the following find command. Don't forget to substitute "<kernel version>" with the version of the kernel you just compiled:
For instance, to automatically load the 3c59x.ko module (which is the driver for a specific 3Com network card family), edit the /etc/conf.d/modules file and enter the module name in it.
Continue the installation with Configuring your System. 8. Configuring your SystemUnder Linux, all partitions used by the system must be listed in /etc/fstab. This file contains the mount points of those partitions (where they are seen in the file system structure), how they should be mounted and with what special options (automatically or not, whether users can mount them or not, etc.) /etc/fstab uses a special syntax. Every line consists of six fields, separated by whitespace (space(s), tabs or a mixture). Each field has its own meaning:
Let us take a look at how we write down the options for the /boot partition. This is just an example, if you didn't or couldn't create a /boot, don't copy it. In our default Alpha partitioning example, /boot is usually the /dev/sda1 partition, with ext2 as filesystem. It needs to be checked during boot, so we would write down:
Some users don't want their /boot partition to be mounted automatically to improve their system's security. Those people should substitute defaults with noauto. This does mean that you need to manually mount this partition every time you want to use it. Add the rules that match your partitioning scheme and append rules for your CD-ROM drive(s), and of course, if you have other partitions or drives, for those too. Now use the example below to create your /etc/fstab:
auto makes mount guess for the filesystem (recommended for removable media as they can be created with one of many filesystems) and user makes it possible for non-root users to mount the CD. To improve performance, most users would want to add the noatime mount option, which results in a faster system since access times aren't registered (you don't need those generally anyway). Double-check your /etc/fstab, save and quit to continue. One of the choices the user has to make is name his/her PC. This seems to be quite easy, but lots of users are having difficulties finding the appropriate name for their Linux-pc. To speed things up, know that any name you choose can be changed afterwards. For all we care, you can just call your system tux and domain homenetwork.
Second, if you need a domainname, set it in /etc/conf.d/net. You only need a domain if your ISP or network administrator says so, or if you have a DNS server but not a DHCP server. You don't need to worry about DNS or domainnames if your networking is setup for DHCP.
If you have a NIS domain (if you don't know what that is, then you don't have one), you need to define that one too:
Before you get that "Hey, we've had that already"-feeling, you should remember that the networking you set up in the beginning of the Gentoo installation was just for the installation. Right now you are going to configure networking for your Gentoo system permanently.
All networking information is gathered in /etc/conf.d/net. It uses a straightforward yet not intuitive syntax if you don't know how to set up networking manually. But don't fear, we'll explain everything. A fully commented example that covers many different configurations is available in /usr/share/doc/openrc-*/net.example.bz2. DHCP is used by default. For DHCP to work, you will need to install a DHCP client. This is described later in Installing Necessary System Tools. Do not forget to install a DHCP client. If you need to configure your network connection either because you need specific DHCP options or because you do not use DHCP at all, open /etc/conf.d/net with your favorite editor (nano is used in this example):
You will see the following file:
To enter your own IP address, netmask and gateway, you need to set both config_eth0 and routes_eth0:
To use DHCP, define config_eth0:
Please read /usr/share/doc/openrc-*/net.example.bz2 for a list of all available options. Be sure to also read your DHCP client manpage if you need to set specific DHCP options. If you have several network interfaces repeat the above steps for config_eth1, config_eth2, etc. Now save the configuration and exit to continue. Automatically Start Networking at Boot To have your network interfaces activated at boot, you need to add them to the default runlevel.
If you have several network interfaces, you need to create the appropriate net.* files just like you did with net.eth0. If you later find out the assumption about the network interface name (which we currently document as eth0) was wrong, then
Writing Down Network Information You now need to inform Linux about your network. This is defined in /etc/hosts and helps in resolving host names to IP addresses for hosts that aren't resolved by your nameserver. You need to define your system. You may also want to define other systems on your network if you don't want to set up your own internal DNS system.
Save and exit the editor to continue. First we set the root password by typing:
Gentoo uses /etc/rc.conf to configure the services, startup, and shutdown of your system. Open up /etc/rc.conf and enjoy all the comments in the file.
When you're finished configuring these two files, save them and exit. Gentoo uses /etc/conf.d/keymaps to handle keyboard configuration. Edit it to configure your keyboard.
Take special care with the keymap variable. If you select the wrong keymap, you will get weird results when typing on your keyboard. When you're finished configuring /etc/conf.d/keymaps, save and exit. Gentoo uses /etc/conf.d/hwclock to set clock options. Edit it according to your needs.
If your hardware clock is not using UTC, you need to add clock="local" to the file. Otherwise you will notice some clock skew. When you're finished configuring /etc/conf.d/hwclock, save and exit. You will probably only use one or maybe two locales on your system. You have to specify locales you will need in /etc/locale.gen.
The following locales are an example to get both English (United States) and German (Germany) with the accompanying character formats (like UTF-8).
The next step is to run locale-gen. It will generates all the locales you have specified in the /etc/locale.gen file.
Once done, you now have the possibility to set the system-wide locale settings in the /etc/env.d/02locale file:
And reload your environment:
We made a full Localization Guide to help you through this process. You can also read our detailed UTF-8 Guide for very specific informations to enable UTF-8 on your system. Please continue with Installing Necessary System Tools. 9. Installing Necessary System ToolsSome tools are missing from the stage3 archive because several packages provide the same functionality. It is now up to you to choose which ones you want to install. The first tool you need to decide on has to provide logging facilities for your system. Unix and Linux have an excellent history of logging capabilities -- if you want you can log everything that happens on your system in logfiles. This happens through the system logger. Gentoo offers several system loggers to choose from. There are sysklogd, which is the traditional set of system logging daemons, syslog-ng, an advanced system logger, and metalog which is a highly-configurable system logger. Others might be available through Portage as well - our number of available packages increases on a daily basis. If you plan on using sysklogd or syslog-ng you might want to install logrotate afterwards as those system loggers don't provide any rotation mechanism for the log files. To install the system logger of your choice, emerge it and have it added to the default runlevel using rc-update. The following example installs syslog-ng. Of course substitute with your system logger:
Next is the cron daemon. Although it is optional and not required for your system, it is wise to install one. But what is a cron daemon? A cron daemon executes scheduled commands. It is very handy if you need to execute some command regularly (for instance daily, weekly or monthly). Gentoo offers three possible cron daemons: dcron, fcron and vixie-cron. Installing one of them is similar to installing a system logger. However, dcron and fcron require an extra configuration command, namely crontab /etc/crontab. If you don't know what to choose, use vixie-cron. We only provide vixie-cron for networkless installations. If you want another cron daemon you can wait and install it later on.
If you want to index your system's files so you are able to quickly locate them using the locate tool, you need to install sys-apps/mlocate.
If you need to access your system remotely after installation, don't forget to add sshd to the default runlevel:
If you need serial console access (which is possible in case of remote servers), you'll need to uncomment the serial console section in /etc/inittab.
The following excerpt shows the uncommented section:
Depending on what file systems you are using, you need to install the necessary file system utilities (for checking the filesystem integrity, creating additional file systems etc.). Please note that tools for managing ext2, ext3 or ext4 filesystems (e2fsprogs) are already installed as a part of the system. The following table lists the tools you need to install if you use a certain file system:
If you don't require any additional networking-related tools (such as ppp or a dhcp client) continue with Configuring the Bootloader. Optional: Installing a DHCP Client If you require Gentoo to automatically obtain an IP address for your network interface(s), you need to install dhcpcd (or any other DHCP client -- see Modular Networking for a list of available DHCP clients). If you don't do this now, you might not be able to connect to the internet after the installation.
Optional: Installing a PPPoE Client If you need ppp to connect to the net, you need to install it.
Now continue with Configuring the Bootloader. 10. Configuring the BootloaderNow that your kernel is configured and compiled and the necessary system configuration files are filled in correctly, it is time to install a program that will fire up your kernel when you start the system. Such a program is called a bootloader. Several bootloaders exist for Linux/Alpha. You must choose one of the supported bootloaders, not all. You have the choice between aBoot and MILO.
We first install aboot on our system. Of course we use emerge to do so:
The next step is to make our bootdisk bootable. This will start aboot when you boot your system. We make our bootdisk bootable by writing the aboot bootloader to the start of the disk.
Although aboot is now installed, we still need to write a configuration file for it. Aboot only requires one line for each configuration, so we can do this:
Additionally, you can make Gentoo boot automatically by setting up some SRM variables. You can try setting these variables from Linux, but it may be easier to do so from the SRM console itself.
If you need to get into the SRM console again in the future (to recover your Gentoo install, play with some variables, or whatever), just hit CTRL+C to abort the automatic loading process. If you're installing using a serial console, don't forget to include the serial console boot flag in aboot.conf. See /etc/aboot.conf.example for some further information. Aboot is now configured and ready to use. Continue with Rebooting the System. Before continuing, you should decide on how to use MILO. In this section, we will assume that you want to make a MILO boot floppy. If you are going to boot from an MS-DOS partition on your hard disk, you should amend the commands appropriately. To install MILO, we use emerge.
After MILO has been installed, the MILO images should be in /opt/milo. The commands below make a bootfloppy for use with MILO. Remember to use the correct image for your Alpha-system.
Your MILO boot floppy is now ready to boot Gentoo Linux. You may need to set environment variables in your ARCS Firmware to get MILO to start; this is all explained in the MILO-HOWTO with some examples on common systems, and examples of the commands to use in interactive mode. Not reading the MILO-HOWTO is a bad idea. Now continue with Rebooting the System. Exit the chrooted environment and unmount all mounted partitions. Then type in that one magical command you have been waiting for: reboot.
Of course, don't forget to remove the bootable CD, otherwise the CD will be booted again instead of your new Gentoo system. Once rebooted in your Gentoo installation, finish up with Finalizing your Gentoo Installation. 11. Finalizing your Gentoo InstallationWorking as root on a Unix/Linux system is dangerous and should be avoided as much as possible. Therefore it is strongly recommended to add a user for day-to-day use. The groups the user is member of define what activities the user can perform. The following table lists a number of important groups you might wish to use:
For instance, to create a user called john who is member of the wheel, users and audio groups, log in as root first (only root can create users) and run useradd:
If a user ever needs to perform some task as root, they can use su - to temporarily receive root privileges. Another way is to use the sudo package which is, if correctly configured, very secure. Now that you've finished installing Gentoo and rebooted, if everything has gone well, you can remove the downloaded stage3 tarball from your hard disk. Remember that they were downloaded to your / directory.
12. Where to go from here?Congratulations! You now have a working Gentoo system. But where to go from here? What are your options now? What to explore first? Gentoo provides its users with lots of possibilities, and therefore lots of documented (and less documented) features. You should definitely take a look at the next part of the Gentoo Handbook entitled Working with Gentoo which explains how to keep your software up to date, how to install more software, what USE flags are, how the Gentoo init system works, etc. If you are interested in optimizing your system for desktop use, or you want to learn how to configure your system to be a full working desktop system, consult our extensive Gentoo Desktop Documentation Resources. Besides, you might want to use our localization guide to make your system feel more at home. We also have a Gentoo Security Handbook which is worth reading. For a full listing of all our available documentation check out our Documentation Resources page. Finally, we also have an official Gentoo Wiki where additional, community-provided documentation can be found. You are of course always welcome on our Gentoo Forums or on one of our many Gentoo IRC channels. We also have several mailing lists open to all our users. Information on how to join is contained in that page. We'll shut up now and let you enjoy your installation. :) B. Working with Gentoo1. A Portage IntroductionPortage is probably Gentoo's most notable innovation in software management. With its high flexibility and enormous amount of features it is frequently seen as the best software management tool available for Linux. Portage is completely written in Python and Bash and therefore fully visible to the users as both are scripting languages. Most users will work with Portage through the emerge tool. This chapter is not meant to duplicate the information available from the emerge man page. For a complete rundown of emerge's options, please consult the man page:
When we talk about packages, we often mean software titles that are available to the Gentoo users through the Portage tree. The Portage tree is a collection of ebuilds, files that contain all information Portage needs to maintain software (install, search, query, ...). These ebuilds reside in /usr/portage by default. Whenever you ask Portage to perform some action regarding software titles, it will use the ebuilds on your system as a base. It is therefore important that you regularly update the ebuilds on your system so Portage knows about new software, security updates, etc. The Portage tree is usually updated with rsync, a fast incremental file transfer utility. Updating is fairly simple as the emerge command provides a front-end for rsync:
If you are unable to rsync due to firewall restrictions you can still update your Portage tree by using our daily generated Portage tree snapshots. The emerge-webrsync tool automatically fetches and installs the latest snapshot on your system:
An additional advantage of using emerge-webrsync is that it allows the administrator to only pull in portage tree snapshots that are signed by the Gentoo release engineering GPG key. More information on this can be found in the Portage Features section on Fetching Validated Portage Tree Snapshots. To search through the Portage tree after software titles, you can use emerge built-in search capabilities. By default, emerge --search returns the names of packages whose title matches (either fully or partially) the given search term. For instance, to search for all packages who have "pdf" in their name:
If you want to search through the descriptions as well you can use the --searchdesc (or -S) switch:
When you take a look at the output, you'll notice that it gives you a lot of information. The fields are clearly labelled so we won't go further into their meanings:
Once you've found a software title to your liking, you can easily install it with emerge: just add the package name. For instance, to install gnumeric:
Since many applications depend on each other, any attempt to install a certain software package might result in the installation of several dependencies as well. Don't worry, Portage handles dependencies well. If you want to find out what Portage would install when you ask it to install a certain package, add the --pretend switch. For instance:
When you ask Portage to install a package, it will download the necessary source code from the internet (if necessary) and store it by default in /usr/portage/distfiles. After this it will unpack, compile and install the package. If you want Portage to only download the sources without installing them, add the --fetchonly option to the emerge command:
Finding Installed Package Documentation Many packages come with their own documentation. Sometimes, the doc USE flag determines whether the package documentation should be installed or not. You can check the existence of a doc USE flag with the emerge -vp <package name> command.
The best way of enabling the doc USE flag is doing it on a per-package basis via /etc/portage/package.use, so that you get documentation only for packages that you are interested in. Enabling this flag globally is known to cause problems with circular dependencies. For more information, please read the USE Flags chapter. Once the package installed, its documentation is generally found in a subdirectory named after the package under the /usr/share/doc directory. You can also list all installed files with the equery tool which is part of the app-portage/gentoolkit package.
When you want to remove a software package from your system, use emerge --unmerge. This will tell Portage to remove all files installed by that package from your system except the configuration files of that application if you have altered those after the installation. Leaving the configuration files allows you to continue working with the package if you ever decide to install it again. However, a big warning applies: Portage will not check if the package you want to remove is required by another package. It will however warn you when you want to remove an important package that breaks your system if you unmerge it.
When you remove a package from your system, the dependencies of that package that were installed automatically when you installed the software are left. To have Portage locate all dependencies that can now be removed, use emerge's --depclean functionality. We will talk about this later on. To keep your system in perfect shape (and not to mention install the latest security updates) you need to update your system regularly. Since Portage only checks the ebuilds in your Portage tree you first have to update your Portage tree. When your Portage tree is updated, you can update your system with emerge --update world. In the next example, we'll also use the --ask switch which will tell Portage to display the list of packages it wants to upgrade and ask you if you want to continue:
Portage will then search for newer version of the applications you have installed. However, it will only verify the versions for the applications you have explicitly installed (the applications listed in /var/lib/portage/world) - it does not thoroughly check their dependencies. If you want to update the dependencies of those packages as well, add the --deep argument:
Still, this doesn't mean all packages: some packages on your system are needed during the compile and build process of packages, but once that package is installed, these dependencies are no longer required. Portage calls those build dependencies. To include those in an update cycle, add --with-bdeps=y:
Since security updates also happen in packages you have not explicitly installed on your system (but that are pulled in as dependencies of other programs), it is recommended to run this command once in a while. If you have altered any of your USE flags lately you might want to add --newuse as well. Portage will then verify if the change requires the installation of new packages or recompilation of existing ones:
Some packages in the Portage tree don't have any real content but are used to install a collection of packages. For instance, the kde-meta package will install a complete KDE environment on your system by pulling in various KDE-related packages as dependencies. If you ever want to remove such a package from your system, running emerge --unmerge on the package won't have much effect as the dependencies remain on the system. Portage has the functionality to remove orphaned dependencies as well, but since the availability of software is dynamically dependent you first need to update your entire system fully, including the new changes you applied when changing USE flags. After this you can run emerge --depclean to remove the orphaned dependencies. When this is done, you need to rebuild the applications that were dynamically linked to the now-removed software titles but don't require them anymore. All this is handled with the following three commands:
revdep-rebuild is provided by the gentoolkit package; don't forget to emerge it first:
Beginning with Portage version 2.1.7, you can accept or reject software installation based on its license. All packages in the tree contain a LICENSE entry in their ebuilds. Running emerge --search packagename will tell you the package's license. By default, Portage permits all licenses, except End User License Agreements (EULAs) that require reading and signing an acceptance agreement. The variable that controls permitted licenses is ACCEPT_LICENSE, which can be set in /etc/portage/make.conf:
With this configuration, packages that require interaction during installation to approve their EULA will not be installed. Packages without an EULA will be installed. You can set ACCEPT_LICENSE globally in /etc/portage/make.conf , or you can specify it on a per-package basis in /etc/portage/package.license. For example, if you want to allow the truecrypt-2.7 license for app-crypt/truecrypt, add the following to /etc/portage/package.license:
This permits installation of truecrypt versions that have the truecrypt-2.7 license, but not versions with the truecrypt-2.8 license.
License groups defined in ACCEPT_LICENSE are prefixed with an @ sign. Here's an example of a system that globally permits the GPL-compatible license group, as well as a few other groups and individual licenses:
If you want only free software and documentation on your system, you might use the following setup:
In this case, "free" is mostly defined by the FSF and OSI. Any package whose license does not meet these requirements will not be installed on your system. 1.e. When Portage is Complaining... About SLOTs, Virtuals, Branches, Architectures and Profiles As we stated before, Portage is extremely powerful and supports many features that other software management tools lack. To understand this, we explain a few aspects of Portage without going into too much detail. With Portage different versions of a single package can coexist on a system. While other distributions tend to name their package to those versions (like freetype and freetype2) Portage uses a technology called SLOTs. An ebuild declares a certain SLOT for its version. Ebuilds with different SLOTs can coexist on the same system. For instance, the freetype package has ebuilds with SLOT="1" and SLOT="2". There are also packages that provide the same functionality but are implemented differently. For instance, metalogd, sysklogd and syslog-ng are all system loggers. Applications that rely on the availability of "a system logger" cannot depend on, for instance, metalogd, as the other system loggers are as good a choice as any. Portage allows for virtuals: each system logger is listed as an "exclusive" dependency of the logging service in the logger virtual package of the virtual category, so that applications can depend on the virtual/logger package. When installed, the package will pull in the first logging package mentioned in the package, unless a logging package was already installed (in which case the virtual is satisfied). Software in the Portage tree can reside in different branches. By default your system only accepts packages that Gentoo deems stable. Most new software titles, when committed, are added to the testing branch, meaning more testing needs to be done before it is marked as stable. Although you will see the ebuilds for those software in the Portage tree, Portage will not update them before they are placed in the stable branch. Some software is only available for a few architectures. Or the software doesn't work on the other architectures, or it needs more testing, or the developer that committed the software to the Portage tree is unable to verify if the package works on different architectures. Each Gentoo installation adheres to a certain profile which contains, amongst other information, the list of packages that are required for a system to function normally.
Ebuilds contain specific fields that inform Portage about its dependencies. There are two possible dependencies: build dependencies, declared in DEPEND and run-time dependencies, declared in RDEPEND. When one of these dependencies explicitly marks a package or virtual as being not compatible, it triggers a blockage. While recent versions of Portage are smart enough to work around minor blockages without user intervention, occasionally you will need to fix it yourself, as explained below. To fix a blockage, you can choose to not install the package or unmerge the conflicting package first. In the given example, you can opt not to install postfix or to remove ssmtp first. You may also see blocking packages with specific atoms, such as <media-video/mplayer-1.0_rc1-r2. In this case, updating to a more recent version of the blocking package would remove the block. It is also possible that two packages that are yet to be installed are blocking each other. In this rare case, you should find out why you need to install both. In most cases you can do with one of the packages alone. If not, please file a bug on Gentoo's bugtracking system.
When you want to install a package that isn't available for your system, you will receive this masking error. You should try installing a different application that is available for your system or wait until the package is put available. There is always a reason why a package is masked:
The error message might also be displayed as follows, if --autounmask isn't set:
Such warning or error occurs when you want to install a package which not only depends on another package, but also requires that that package is built with a particular USE flag (or set of USE flags). In the given example, the package app-text/feelings needs to be built with USE="test", but this USE flag is not set on the system. To resolve this, either add the requested USE flag to your global USE flags in /etc/portage/make.conf, or set it for the specific package in /etc/portage/package.use.
The application you are trying to install depends on another package that is not available for your system. Please check bugzilla if the issue is known and if not, please report it. Unless you are mixing branches this should not occur and is therefore a bug.
The application you want to install has a name that corresponds with more than one package. You need to supply the category name as well. Portage will inform you of possible matches to choose from.
Two (or more) packages you want to install depend on each other and can therefore not be installed. This is most likely a bug in the Portage tree. Please resync after a while and try again. You can also check bugzilla if the issue is known and if not, report it.
Portage was unable to download the sources for the given application and will try to continue installing the other applications (if applicable). This failure can be due to a mirror that has not synchronised correctly or because the ebuild points to an incorrect location. The server where the sources reside can also be down for some reason. Retry after one hour to see if the issue still persists.
You have asked to remove a package that is part of your system's core packages. It is listed in your profile as required and should therefore not be removed from the system. Sometimes, when you attempt to emerge a package, it will fail with the message:
This is a sign that something is wrong with the Portage tree -- often, it is because a developer may have made a mistake when committing a package to the tree. When the digest verification fails, do not try to re-digest the package yourself. Running ebuild foo manifest will not fix the problem; it will almost certainly make it worse! Instead, wait an hour or two for the tree to settle down. It's likely that the error was noticed right away, but it can take a little time for the fix to trickle down the Portage tree. While you're waiting, check Bugzilla and see if anyone has reported the problem yet. If not, go ahead and file a bug for the broken package. Once you see that the bug has been fixed, you may want to re-sync to pick up the fixed digest.
2. USE flagsWhen you are installing Gentoo (or any other distribution, or even operating system for that matter) you make choices depending on the environment you are working with. A setup for a server differs from a setup for a workstation. A gaming workstation differs from a 3D rendering workstation. This is not only true for choosing what packages you want to install, but also what features a certain package should support. If you don't need OpenGL, why would you bother installing OpenGL and build OpenGL support in most of your packages? If you don't want to use KDE, why would you bother compiling packages with KDE support if those packages work flawlessly without? To help users in deciding what to install/activate and what not, we wanted the user to specify his/her environment in an easy way. This forces the user into deciding what they really want and eases the process for Portage, our package management system, to make useful decisions. Enter the USE flags. Such a flag is a keyword that embodies support and dependency-information for a certain concept. If you define a certain USE flag, Portage will know that you want support for the chosen keyword. Of course this also alters the dependency information for a package. Let us take a look at a specific example: the kde keyword. If you do not have this keyword in your USE variable, all packages that have optional KDE support will be compiled without KDE support. All packages that have an optional KDE dependency will be installed without installing the KDE libraries (as dependency). If you have defined the kde keyword, then those packages will be compiled with KDE support, and the KDE libraries will be installed as dependency. By correctly defining the keywords you will receive a system tailored specifically to your needs. There are two types of USE flags: global and local USE flags.
A list of available global USE flags can be found online or locally in /usr/portage/profiles/use.desc. A list of available local USE flags can be found locally in /usr/portage/profiles/use.local.desc. In the hope you are convinced of the importance of USE flags we will now inform you how to declare USE flags. As previously mentioned, all USE flags are declared inside the USE variable. To make it easy for users to search and pick USE flags, we already provide a default USE setting. This setting is a collection of USE flags we think are commonly used by the Gentoo users. This default setting is declared in the make.defaults files part of your profile. The profile your system listens to is pointed to by the /etc/portage/make.profile symlink. Each profile works on top of another, larger profile, the end result is therefore the sum of all profiles. The top profile is the base profile (/usr/portage/profiles/base). Let us take a look at this default setting for the 13.0 profile:
As you can see, this variable already contains quite a lot of keywords. Do not alter any make.defaults file to tailor the USE variable to your needs: changes in this file will be undone when you update Portage! To change this default setting, you need to add or remove keywords to the USE variable. This is done globally by defining the USE variable in /etc/portage/make.conf. In this variable you add the extra USE flags you require, or remove the USE flags you don't want. This latter is done by prefixing the keyword with the minus-sign ("-"). For instance, to remove support for KDE and QT but add support for ldap, the following USE can be defined in /etc/portage/make.conf:
Declaring USE flags for individual packages Sometimes you want to declare a certain USE flag for one (or a couple) of applications but not system-wide. To accomplish this, you will need to create the /etc/portage directory (if it doesn't exist yet) and edit /etc/portage/package.use. This is usually a single file, but can also be a directory; see man portage for more information. The following examples assume package.use is a single file. For instance, if you don't want berkdb support globally but you do want it for mysql, you would add:
You can of course also explicitly disable USE flags for a certain application. For instance, if you don't want java support in PHP:
Sometimes you want to set a certain USE setting only once. Instead of editing /etc/portage/make.conf twice (to do and undo the USE changes) you can just declare the USE variable as environment variable. Remember that, when you re-emerge or update this application (either explicitly or as part of a system update) your changes will be lost! As an example we will temporarily remove java from the USE setting during the installation of seamonkey.
Of course there is a certain precedence on what setting has priority over the USE setting. You don't want to declare USE="-java" only to see that java is still used due to a setting that has a higher priority. The precedence for the USE setting is, ordered by priority (first has lowest priority):
To view the final USE setting as seen by Portage, run emerge --info. This will list all relevant variables (including the USE variable) with the content used by Portage.
Adapting your Entire System to New USE Flags If you have altered your USE flags and you wish to update your entire system to use the new USE flags, use emerge's --newuse option:
Next, run Portage's depclean to remove the conditional dependencies that were emerged on your "old" system but that have been obsoleted by the new USE flags.
When depclean has finished, run revdep-rebuild to rebuild the applications that are dynamically linked against shared objects provided by possibly removed packages. revdep-rebuild is part of the gentoolkit package; don't forget to emerge it first.
When all this is accomplished, your system is using the new USE flag settings. 2.c. Package specific USE flags Let us take the example of seamonkey: what USE flags does it listen to? To find out, we use emerge with the --pretend and --verbose options:
emerge isn't the only tool for this job. In fact, we have a tool dedicated to package information called equery which resides in the gentoolkit package. First, install gentoolkit:
Now run equery with the uses argument to view the USE flags of a certain package. For instance, for the gnumeric package:
3. Portage FeaturesPortage has several additional features that makes your Gentoo experience even better. Many of these features rely on certain software tools that improve performance, reliability, security, ... To enable or disable certain Portage features you need to edit /etc/portage/make.conf's FEATURES variable which contains the various feature keywords, separated by white space. In several cases you will also need to install the additional tool on which the feature relies. Not all features that Portage supports are listed here. For a full overview, please consult the make.conf man page:
To find out what FEATURES are default set, run emerge --info and search for the FEATURES variable or grep it out:
distcc is a program to distribute compilations across several, not necessarily identical, machines on a network. The distcc client sends all necessary information to the available distcc servers (running distccd) so they can compile pieces of source code for the client. The net result is a faster compilation time. You can find more information about distcc (and how to have it work with Gentoo) in our Gentoo Distcc Documentation. Distcc ships with a graphical monitor to monitor tasks that your computer is sending away for compilation. If you use Gnome then put 'gnome' in your USE variable. However, if you don't use Gnome and would still like to have the monitor then you should put 'gtk' in your USE variable.
Add distcc to the FEATURES variable inside /etc/portage/make.conf. Next, edit the MAKEOPTS variable to your liking. A known guideline is to fill in "-jX" with X the number of CPUs that run distccd (including the current host) plus one, but you might have better results with other numbers. Now run distcc-config and enter the list of available distcc servers. For a simple example we assume that the available DistCC servers are 192.168.1.102 (the current host), 192.168.1.103 and 192.168.1.104 (two "remote" hosts):
Don't forget to run the distccd daemon as well:
ccache is a fast compiler cache. When you compile a program, it will cache intermediate results so that, whenever you recompile the same program, the compilation time is greatly reduced. The first time you run ccache, it will be much slower than a normal compilation. Subsequent recompiles should be faster. ccache is only helpful if you will be recompiling the same application many times; thus it's mostly only useful for software developers. If you are interested in the ins and outs of ccache, please visit the ccache homepage.
To install ccache, run emerge ccache:
Open /etc/portage/make.conf and add ccache to the FEATURES variable. Next, add a new variable called CCACHE_SIZE and set it to "2G":
To check if ccache functions, ask ccache to provide you with its statistics. Because Portage uses a different ccache home directory, you need to set the CCACHE_DIR variable as well:
The /var/tmp/ccache location is Portage' default ccache home directory; if you want to alter this setting you can set the CCACHE_DIR variable in /etc/portage/make.conf. However, if you would run ccache, it would use the default location of ${HOME}/.ccache, which is why you needed to set the CCACHE_DIR variable when asking for the (Portage) ccache statistics. Using ccache for non-Portage C Compiling If you would like to use ccache for non-Portage compilations, add /usr/lib/ccache/bin to the beginning of your PATH variable (before /usr/bin). This can be accomplished by editing .bash_profile in your user's home directory. Using .bash_profile is one way to define PATH variables.
Portage supports the installation of prebuilt packages. Even though Gentoo does not provide prebuilt packages by itself (except for the GRP snapshots) Portage can be made fully aware of prebuilt packages. To create a prebuilt package you can use quickpkg if the package is already installed on your system, or emerge with the --buildpkg or --buildpkgonly options. If you want Portage to create prebuilt packages of every single package you install, add buildpkg to the FEATURES variable. More extended support for creating prebuilt package sets can be obtained with catalyst. For more information on catalyst please read the Catalyst Frequently Asked Questions. Although Gentoo doesn't provide one, you can create a central repository where you store prebuilt packages. If you want to use this repository, you need to make Portage aware of it by having the PORTAGE_BINHOST variable point to it. For instance, if the prebuilt packages are on ftp://buildhost/gentoo:
When you want to install a prebuilt package, add the --getbinpkg option to the emerge command alongside of the --usepkg option. The former tells emerge to download the prebuilt package from the previously defined server while the latter asks emerge to try to install the prebuilt package first before fetching the sources and compiling it. For instance, to install gnumeric with prebuilt packages:
More information about emerge's prebuilt package options can be found in the emerge man page:
When you are emerging a series of packages, Portage can fetch the source files for the next package in the list even while it is compiling another package, thus shortening compile times. To make use of this capability, add "parallel-fetch" to your FEATURES. Note that this is on by default, so you shouldn't need to specifically enable it. When Portage is run as root, FEATURES="userfetch" will allow Portage to drop root privileges while fetching package sources. This is a small security improvement. 3.f. Pulling Validated Portage Tree Snapshots As an administrator, you can opt to only update your local Portage tree with a cryptographically validated Portage tree snapshot as released by the Gentoo infrastructure. This ensures that no rogue rsync mirror is adding unwanted code or packages in the tree you are downloading. To configure Portage, first create a truststore in which you download and accept the keys of the Gentoo Infrastructure responsible for signing the Portage tree snapshots. Of course, if you want to, you can validate this GPG key as per the proper guidelines (like checking the key fingerprint). You can find the list of GPG keys used by the release engineering team on their project page.
Next, edit /etc/portage/make.conf and enable support for validating the signed Portage tree snapshots (using FEATURES="webrsync-gpg") and disabling updating the Portage tree using the regular emerge --sync method.
That's it. Next time you run emerge-webrsync, only the snapshots with a valid signature will be expanded on your file system. 4. InitscriptsWhen you boot your system, you will notice lots of text floating by. If you pay close attention, you will notice this text is the same every time you reboot your system. The sequence of all these actions is called the boot sequence and is (more or less) statically defined. First, your boot loader will load the kernel image you have defined in the boot loader configuration into memory after which it tells the CPU to run the kernel. When the kernel is loaded and run, it initializes all kernel-specific structures and tasks and starts the init process. This process then makes sure that all filesystems (defined in /etc/fstab) are mounted and ready to be used. Then it executes several scripts located in /etc/init.d, which will start the services you need in order to have a successfully booted system. Finally, when all scripts are executed, init activates the terminals (in most cases just the virtual consoles which are hidden beneath Alt-F1, Alt-F2, etc.) attaching a special process called agetty to it. This process will then make sure you are able to log on through these terminals by running login. Now init doesn't just execute the scripts in /etc/init.d randomly. Even more, it doesn't run all scripts in /etc/init.d, only the scripts it is told to execute. It decides which scripts to execute by looking into /etc/runlevels. First, init runs all scripts from /etc/init.d that have symbolic links inside /etc/runlevels/boot. Usually, it will start the scripts in alphabetical order, but some scripts have dependency information in them, telling the system that another script must be run before they can be started. When all /etc/runlevels/boot referenced scripts are executed, init continues with running the scripts that have a symbolic link to them in /etc/runlevels/default. Again, it will use the alphabetical order to decide what script to run first, unless a script has dependency information in it, in which case the order is changed to provide a valid start-up sequence. Of course init doesn't decide all that by itself. It needs a configuration file that specifies what actions need to be taken. This configuration file is /etc/inittab. If you remember the boot sequence we have just described, you will remember that init's first action is to mount all filesystems. This is defined in the following line from /etc/inittab:
This line tells init that it must run /sbin/rc sysinit to initialize the system. The /sbin/rc script takes care of the initialisation, so you might say that init doesn't do much -- it delegates the task of initialising the system to another process. Second, init executed all scripts that had symbolic links in /etc/runlevels/boot. This is defined in the following line:
Again the rc script performs the necessary tasks. Note that the option given to rc (boot) is the same as the subdirectory of /etc/runlevels that is used. Now init checks its configuration file to see what runlevel it should run. To decide this, it reads the following line from /etc/inittab:
In this case (which the majority of Gentoo users will use), the runlevel id is 3. Using this information, init checks what it must run to start runlevel 3:
The line that defines level 3, again, uses the rc script to start the services (now with argument default). Again note that the argument of rc is the same as the subdirectory from /etc/runlevels. When rc has finished, init decides what virtual consoles it should activate and what commands need to be run at each console:
You have seen that init uses a numbering scheme to decide what runlevel it should activate. A runlevel is a state in which your system is running and contains a collection of scripts (runlevel scripts or initscripts) that must be executed when you enter or leave a runlevel. In Gentoo, there are seven runlevels defined: three internal runlevels, and four user-defined runlevels. The internal runlevels are called sysinit, shutdown and reboot and do exactly what their names imply: initialize the system, powering off the system and rebooting the system. The user-defined runlevels are those with an accompanying /etc/runlevels subdirectory: boot, default, nonetwork and single. The boot runlevel starts all system-necessary services which all other runlevels use. The remaining three runlevels differ in what services they start: default is used for day-to-day operations, nonetwork is used in case no network connectivity is required, and single is used when you need to fix the system. The scripts that the rc process starts are called init scripts. Each script in /etc/init.d can be executed with the arguments start, stop, restart, pause, zap, status, ineed, iuse, needsme, usesme or broken. To start, stop or restart a service (and all depending services), start, stop and restart should be used:
If you want to stop a service, but not the services that depend on it, you can use the pause argument:
If you want to see what status a service has (started, stopped, paused, ...) you can use the status argument:
If the status information tells you that the service is running, but you know that it is not, then you can reset the status information to "stopped" with the zap argument:
To also ask what dependencies the service has, you can use iuse or ineed. With ineed you can see the services that are really necessary for the correct functioning of the service. iuse on the other hand shows the services that can be used by the service, but are not necessary for the correct functioning.
Similarly, you can ask what services require the service (needsme) or can use it (usesme):
Finally, you can ask what dependencies the service requires that are missing:
Gentoo's init system uses a dependency-tree to decide what service needs to be started first. As this is a tedious task that we wouldn't want our users to have to do manually, we have created tools that ease the administration of the runlevels and init scripts. With rc-update you can add and remove init scripts to a runlevel. The rc-update tool will then automatically ask the depscan.sh script to rebuild the dependency tree. You have already added init scripts to the "default" runlevel during the installation of Gentoo. At that time you might not have had a clue what the "default" is for, but now you should. The rc-update script requires a second argument that defines the action: add, del or show. To add or remove an init script, just give rc-update the add or del argument, followed by the init script and the runlevel. For instance:
The rc-update -v show command will show all the available init scripts and list at which runlevels they will execute:
You can also run rc-update show (without -v) to just view enabled init scripts and their runlevels. Why the Need for Extra Configuration? Init scripts can be quite complex. It is therefore not really desirable to have the users edit the init script directly, as it would make it more error-prone. It is however important to be able to configure such a service. For instance, you might want to give more options to the service itself. A second reason to have this configuration outside the init script is to be able to update the init scripts without the fear that your configuration changes will be undone. Gentoo provides an easy way to configure such a service: every init script that can be configured has a file in /etc/conf.d. For instance, the apache2 initscript (called /etc/init.d/apache2) has a configuration file called /etc/conf.d/apache2, which can contain the options you want to give to the Apache 2 server when it is started:
Such a configuration file contains variables and variables alone (just like /etc/portage/make.conf), making it very easy to configure services. It also allows us to provide more information about the variables (as comments). No, writing an init script is usually not necessary as Gentoo provides ready-to-use init scripts for all provided services. However, you might have installed a service without using Portage, in which case you will most likely have to create an init script. Do not use the init script provided by the service if it isn't explicitly written for Gentoo: Gentoo's init scripts are not compatible with the init scripts used by other distributions! The basic layout of an init script is shown below.
Any init script requires the start() function to be defined. All other sections are optional. There are two dependency-alike settings you can define that influence the start-up or sequencing of init scripts: use and need. Next to these two, there are also two order-influencing methods called before and after. These last two are no dependencies per se - they do not make the original init script fail if the selected one isn't scheduled to start (or fails to start).
It should be clear from the above that need is the only "true" dependency setting as it affects if the script will be started or not. All the others are merely pointers towards the init system to clarify in which order scripts can be (or should be) launched. Now, if you look at many of Gentoo's available init scripts, you will notice that some have dependencies on things that are no init scripts. These "things" we call virtuals. A virtual dependency is a dependency that a service provides, but that is not provided solely by that service. Your init script can depend on a system logger, but there are many system loggers available (metalogd, syslog-ng, sysklogd, ...). As you cannot need every single one of them (no sensible system has all these system loggers installed and running) we made sure that all these services provide a virtual dependency. Let us take a look at the dependency information for the postfix service.
As you can see, the postfix service:
As we described in the previous section, you can tell the init system what order it should use for starting (or stopping) scripts. This ordering is handled both through the dependency settings use and need, but also through the order settings before and after. As we have described these earlier already, let's take a look at the Portmap service as an example of such init script.
You can also use the "*" glob to catch all services in the same runlevel, although this isn't advisable.
If your service must write to local disks, it should need localmount. If it places anything in /var/run such as a pidfile, then it should start after bootmisc:
Next to the depend() functionality, you also need to define the start() function. This one contains all the commands necessary to initialize your service. It is advisable to use the ebegin and eend functions to inform the user about what is happening:
Both --exec and --pidfile should be used in start and stop functions. If the service does not create a pidfile, then use --make-pidfile if possible, though you should test this to be sure. Otherwise, don't use pidfiles. You can also add --quiet to the start-stop-daemon options, but this is not recommended unless the service is extremely verbose. Using --quiet may hinder debugging if the service fails to start. Another notable setting used in the above example is to check the contents of the RC_CMD variable. Unlike the previous init script system, the newer openrc system does not support script-specific restart functionality. Instead, the script needs to check the contents of the RC_CMD variable to see if a function (be it start() or stop()) is called as part of a restart or not.
If you need more examples of the start() function, please read the source code of the available init scripts in your /etc/init.d directory. Another function you can define is stop(). You are not obliged to define this function though! Our init system is intelligent enough to fill in this function by itself if you use start-stop-daemon. Here is an example of a stop() function:
If your service runs some other script (for example, bash, python, or perl), and this script later changes names (for example, foo.py to foo), then you will need to add --name to start-stop-daemon. You must specify the name that your script will be changed to. In this example, a service starts foo.py, which changes names to foo:
start-stop-daemon has an excellent man page available if you need more information:
Gentoo's init script syntax is based on the POSIX Shell so you are free to use sh-compatible constructs inside your init script. Keep other constructs, like bash-specific ones, out of the init scripts to ensure that the scripts remain functional regardless of the change Gentoo might do on its init system. If you want your init script to support more options than the ones we have already encountered, you should add the option to the extra_commands variable, and create a function with the same name as the option. For instance, to support an option called restartdelay:
Service Configuration Variables You don't have to do anything to support a configuration file in /etc/conf.d: if your init script is executed, the following files are automatically sourced (i.e. the variables are available to use):
Also, if your init script provides a virtual dependency (such as net), the file associated with that dependency (such as /etc/conf.d/net) will be sourced too. 4.e. Changing the Runlevel Behaviour Many laptop users know the situation: at home you need to start net.eth0 while you don't want to start net.eth0 while you're on the road (as there is no network available). With Gentoo you can alter the runlevel behaviour to your own will. For instance you can create a second "default" runlevel which you can boot that has other init scripts assigned to it. You can then select at boottime what default runlevel you want to use. First of all, create the runlevel directory for your second "default" runlevel. As an example we create the offline runlevel:
Add the necessary init scripts to the newly created runlevels. For instance, if you want to have an exact copy of your current default runlevel but without net.eth0:
Even though net.eth0 has been removed from the offline runlevel, udev might want to attempt to start any devices it detects and launch the appropriate services, a functionality that is called hotplugging. By default, Gentoo does not enable hotplugging. If you do want to enable hotplugging, but only for a selected set of scripts, use the rc_hotplug variable in /etc/rc.conf:
Now edit your bootloader configuration and add a new entry for the offline runlevel. For instance, in /boot/grub/grub.conf:
Voilà, you're all set now. If you boot your system and select the newly added entry at boot, the offline runlevel will be used instead of the default one. Using bootlevel is completely analogous to softlevel. The only difference here is that you define a second "boot" runlevel instead of a second "default" runlevel. 5. Environment VariablesAn environment variable is a named object that contains information used by one or more applications. Many users (and especially those new to Linux) find this a bit weird or unmanageable. However, this is a mistake: by using environment variables one can easily change a configuration setting for one or more applications. The following table lists a number of variables used by a Linux system and describes their use. Example values are presented after the table.
Below you will find an example definition of all these variables:
5.b. Defining Variables Globally To centralise the definitions of these variables, Gentoo introduced the /etc/env.d directory. Inside this directory you will find a number of files, such as 00basic, 05gcc, etc. which contain the variables needed by the application mentioned in their name. For instance, when you installed gcc, a file called 05gcc was created by the ebuild which contains the definitions of the following variables:
Other distributions tell you to change or add such environment variable definitions in /etc/profile or other locations. Gentoo on the other hand makes it easy for you (and for Portage) to maintain and manage the environment variables without having to pay attention to the numerous files that can contain environment variables. For instance, when gcc is updated, the /etc/env.d/05gcc file is updated too without requesting any user-interaction. This not only benefits Portage, but also you, as user. Occasionally you might be asked to set a certain environment variable system-wide. As an example we take the http_proxy variable. Instead of messing about with /etc/profile, you can now just create a file (/etc/env.d/99local) and enter your definition(s) in it:
By using the same file for all your variables, you have a quick overview on the variables you have defined yourself. Several files in /etc/env.d define the PATH variable. This is not a mistake: when you run env-update, it will append the several definitions before it updates the environment variables, thereby making it easy for packages (or users) to add their own environment variable settings without interfering with the already existing values. The env-update script will append the values in the alphabetical order of the /etc/env.d files. The file names must begin with two decimal digits.
The concatenation of variables does not always happen, only with the following variables: ADA_INCLUDE_PATH, ADA_OBJECTS_PATH, CLASSPATH, KDEDIRS, PATH, LDPATH, MANPATH, INFODIR, INFOPATH, ROOTPATH, CONFIG_PROTECT, CONFIG_PROTECT_MASK, PRELINK_PATH, PRELINK_PATH_MASK, PKG_CONFIG_PATH and PYTHONPATH. For all other variables the latest defined value (in alphabetical order of the files in /etc/env.d) is used. You can add more variables into this list of concatenate-variables by adding the variable name to either COLON_SEPARATED or SPACE_SEPARATED variables (also inside an env.d file). When you run env-update, the script will create all environment variables and place them in /etc/profile.env (which is used by /etc/profile). It will also extract the information from the LDPATH variable and use that to create /etc/ld.so.conf. After this, it will run ldconfig to recreate the /etc/ld.so.cache file used by the dynamical linker. If you want to notice the effect of env-update immediately after you run it, execute the following command to update your environment. Users who have installed Gentoo themselves will probably remember this from the installation instructions:
5.c. Defining Variables Locally You do not always want to define an environment variable globally. For instance, you might want to add /home/my_user/bin and the current working directory (the directory you are in) to the PATH variable but don't want all other users on your system to have that in their PATH too. If you want to define an environment variable locally, you should use ~/.bashrc or ~/.bash_profile:
When you relogin, your PATH variable will be updated. Sometimes even stricter definitions are requested. You might want to be able to use binaries from a temporary directory you created without using the path to the binaries themselves or editing ~/.bashrc for the short time you need it. In this case, you can just define the PATH variable in your current session by using the export command. As long as you don't log out, the PATH variable will be using the temporary settings.
C. Working with Portage1. Files and DirectoriesPortage comes with a default configuration stored in /etc/make.globals. When you take a look at it, you'll notice that all Portage configuration is handled through variables. What variables Portage listens to and what they mean are described later. Since many configuration directives differ between architectures, Portage also has default configuration files which are part of your profile. Your profile is pointed to by the /etc/portage/make.profile symlink; Portage' configurations are set in the make.defaults files of your profile and all parent profiles. We'll explain more about profiles and the /etc/portage/make.profile directory later on. If you're planning on changing a configuration variable, don't alter /etc/make.globals or make.defaults. Instead use /etc/portage/make.conf which has precedence over the previous files. You'll also find a /usr/share/portage/config/make.conf.example. As the name implies, this is merely an example file - Portage does not read in this file. You can also define a Portage configuration variable as an environment variable, but we don't recommend this. We've already encountered the /etc/portage/make.profile directory. Well, this isn't exactly a directory but a symbolic link to a profile, by default one inside /usr/portage/profiles although you can create your own profiles elsewhere and point to them. The profile this symlink points to is the profile to which your system adheres. A profile contains architecture-specific information for Portage, such as a list of packages that belong to the system corresponding with that profile, a list of packages that don't work (or are masked-out) for that profile, etc. When you need to override Portage's behaviour regarding the installation of software, you will end up editing files within /etc/portage. You are highly recommended to use files within /etc/portage and highly discouraged to override the behaviour through environment variables! Within /etc/portage you can create the following files:
These don't have to be files; they can also be directories that contain one file per package. More information about the /etc/portage directory and a full list of possible files you can create can be found in the Portage man page:
Changing Portage File & Directory Locations The previously mentioned configuration files cannot be stored elsewhere - Portage will always look for those configuration files at those exact locations. However, Portage uses many other locations for various purposes: build directory, source code storage, Portage tree location, ... All these purposes have well-known default locations but can be altered to your own taste through /etc/portage/make.conf. The rest of this chapter explains what special-purpose locations Portage uses and how to alter their placement on your filesystem. This document isn't meant to be used as a reference though. If you need 100% coverage, please consult the Portage and make.conf man pages:
The Portage tree default location is /usr/portage. This is defined by the PORTDIR variable. When you store the Portage tree elsewhere (by altering this variable), don't forget to change the /etc/portage/make.profile symbolic link accordingly. If you alter the PORTDIR variable, you might want to alter the following variables as well since they will not notice the PORTDIR change. This is due to how Portage handles variables: PKGDIR, DISTDIR, RPMDIR. Even though Portage doesn't use prebuilt binaries by default, it has extensive support for them. When you ask Portage to work with prebuilt packages, it will look for them in /usr/portage/packages. This location is defined by the PKGDIR variable. Application source code is stored in /usr/portage/distfiles by default. This location is defined by the DISTDIR variable. Portage stores the state of your system (what packages are installed, what files belong to which package, ...) in /var/db/pkg. Do not alter these files manually! It might break Portage's knowledge of your system. The Portage cache (with modification times, virtuals, dependency tree information, ...) is stored in /var/cache/edb. This location really is a cache: you can clean it if you are not running any portage-related application at that moment. Portage's temporary files are stored in /var/tmp by default. This is defined by the PORTAGE_TMPDIR variable. If you alter the PORTAGE_TMPDIR variable, you might want to alter the following variables as well since they will not notice the PORTAGE_TMPDIR change. This is due to how Portage handles variables: BUILD_PREFIX. Portage creates specific build directories for each package it emerges inside /var/tmp/portage. This location is defined by the BUILD_PREFIX variable. By default Portage installs all files on the current filesystem (/), but you can change this by setting the ROOT environment variable. This is useful when you want to create new build images. Portage can create per-ebuild logfiles, but only when the PORT_LOGDIR variable is set to a location that is writable by Portage (the portage user). By default this variable is unset. If you don't set PORT_LOGDIR, then you won't receive any build logs with the current logging system, though you may receive some logs from the new elog. If you do have PORT_LOGDIR defined and you use elog, you will receive build logs and any logs saved by elog, as explained below. Portage offers fine-grained control over logging through the use of elog:
2. Configuring through VariablesAs noted previously, Portage is configurable through many variables which you should define in /etc/portage/make.conf. Please refer to the make.conf man page for more and complete information:
Configure and Compiler Options When Portage builds applications, it passes the contents of the following variables to the compiler and configure script:
The USE variable is also used during configure and compilations but has been explained in great detail in previous chapters. When Portage has merged a newer version of a certain software title, it will remove the obsoleted files of the older version from your system. Portage gives the user a 5 second delay before unmerging the older version. These 5 seconds are defined by the CLEAN_DELAY variable. You can tell emerge to use certain options every time it is run by setting EMERGE_DEFAULT_OPTS. Some useful options would be --ask, --verbose, --tree, and so on. 2.c. Configuration File Protection Portage overwrites files provided by newer versions of a software title if the files aren't stored in a protected location. These protected locations are defined by the CONFIG_PROTECT variable and are generally configuration file locations. The directory listing is space-delimited. A file that would be written in such a protected location is renamed and the user is warned about the presence of a newer version of the (presumable) configuration file. You can find out about the current CONFIG_PROTECT setting from the emerge --info output:
More information about Portage's Configuration File Protection is available in the CONFIGURATION FILES section of the emerge manpage:
To 'unprotect' certain subdirectories of protected locations you can use the CONFIG_PROTECT_MASK variable. When the requested information or data is not available on your system, Portage will retrieve it from the Internet. The server locations for the various information and data channels are defined by the following variables:
A third setting involves the location of the rsync server which you use when you update your Portage tree:
The GENTOO_MIRRORS and SYNC variables can be set automatically through the mirrorselect application. You need to emerge mirrorselect first before you can use it. For more information, see mirrorselect's online help:
If your environment requires you to use a proxy server, you can use the http_proxy, ftp_proxy and RSYNC_PROXY variables to declare a proxy server. When Portage needs to fetch source code, it uses wget by default. You can change this through the FETCHCOMMAND variable. Portage is able to resume partially downloaded source code. It uses wget by default, but this can be altered through the RESUMECOMMAND variable. Make sure that your FETCHCOMMAND and RESUMECOMMAND stores the source code in the correct location. Inside the variables you should use \${URI} and \${DISTDIR} to point to the source code location and distfiles location respectively. You can also define protocol-specific handlers with FETCHCOMMAND_HTTP, FETCHCOMMAND_FTP, RESUMECOMMAND_HTTP, RESUMECOMMAND_FTP, and so on. You cannot alter the rsync command used by Portage to update the Portage tree, but you can set some variables related to the rsync command:
For more information on these options and others, please read man rsync. You can change your default branch with the ACCEPT_KEYWORDS variable. It defaults to your architecture's stable branch. More information on Gentoo's branches can be found in the next chapter. You can activate certain Portage features through the FEATURES variable. The Portage Features have been discussed in previous chapters, such as Portage Features. With the PORTAGE_NICENESS variable you can augment or reduce the nice value Portage runs with. The PORTAGE_NICENESS value is added to the current nice value. For more information about nice values, see the nice man page:
The NOCOLOR, which defaults to "false", defines if Portage should disable the use of coloured output. 3. Mixing Software BranchesThe ACCEPT_KEYWORDS variable defines what software branch you use on your system. It defaults to the stable software branch for your architecture, for instance x86. We recommend that you only use the stable branch. However, if you don't care about stability this much and you want to help out Gentoo by submitting bugreports to http://bugs.gentoo.org, read on. If you want to use more recent software, you can consider using the testing branch instead. To have Portage use the testing branch, add a ~ in front of your architecture. The testing branch is exactly what it says - Testing. If a package is in testing, it means that the developers feel that it is functional but has not been thoroughly tested. You could very well be the first to discover a bug in the package in which case you could file a bugreport to let the developers know about it. Beware though, you might notice stability issues, imperfect package handling (for instance wrong/missing dependencies), too frequent updates (resulting in lots of building) or broken packages. If you do not know how Gentoo works and how to solve problems, we recommend that you stick with the stable and tested branch. For example, to select the testing branch for the x86 architecture, edit /etc/portage/make.conf and set:
If you update your system now, you will find out that lots of packages will be updated. Mind you though: when you have updated your system to use the testing branch there is usually no easy way back to the stable, official branch (except for using backups of course). 3.b. Mixing Stable with Testing The package.accept_keywords location You can ask Portage to allow the testing branch for particular packages but use the stable branch for the rest of the system. To achieve this, add the package category and name you want to use the testing branch of in /etc/portage/package.accept_keywords. You can also create a directory (with the same name) and list the package in the files under that directory. For instance, to use the testing branch for gnumeric:
If you want to use a specific software version from the testing branch but you don't want Portage to use the testing branch for subsequent versions, you can add in the version in the package.accept_keywords location. In this case you must use the = operator. You can also enter a version range using the <=, <, > or >= operators. In any case, if you add version information, you must use an operator. If you leave out version information, you cannot use an operator. In the following example we ask Portage to accept gnumeric-1.2.13:
When a package has been masked by the Gentoo developers and you still want to use it despite the reason mentioned in the package.mask file (situated in /usr/portage/profiles by default), add the desired version (usually this will be the exact same line from profiles) in the /etc/portage/package.unmask file (or in a file in that directory if it is a directory). For instance, if =net-mail/hotwayd-0.8 is masked, you can unmask it by adding the exact same line in the package.unmask location:
When you don't want Portage to take a certain package or a specific version of a package into account you can mask it yourself by adding an appropriate line to the /etc/portage/package.mask location (either in that file or in a file in this directory). For instance, if you don't want Portage to install newer kernel sources than gentoo-sources-2.6.8.1, you add the following line at the package.mask location:
4. Additional Portage Toolsdispatch-conf is a tool that aids in merging the ._cfg0000_<name> files. ._cfg0000_<name> files are generated by Portage when it wants to overwrite a file in a directory protected by the CONFIG_PROTECT variable. With dispatch-conf, you are able to merge updates to your configuration files while keeping track of all changes. dispatch-conf stores the differences between the configuration files as patches or by using the RCS revision system. This means that if you make a mistake when updating a config file, you can revert to the previous version of your config file at any time. When using dispatch-conf, you can ask to keep the configuration file as-is, use the new configuration file, edit the current one or merge the changes interactively. dispatch-conf also has some nice additional features:
Make certain you edit /etc/dispatch-conf.conf first and create the directory referenced by the archive-dir variable.
When running dispatch-conf, you'll be taken through each changed config file, one at a time. Press u to update (replace) the current config file with the new one and continue to the next file. Press z to zap (delete) the new config file and continue to the next file. Once all config files have been taken care of, dispatch-conf will exit. You can also press q to exit any time. For more information, check out the dispatch-conf man page. It tells you how to interactively merge current and new config files, edit new config files, examine differences between files, and more.
You can also use etc-update to merge config files. It's not as simple to use as dispatch-conf, nor as featureful, but it does provide an interactive merging setup and can also auto-merge trivial changes. However, unlike dispatch-conf, etc-update does not preserve the old versions of your config files. Once you update the file, the old version is gone forever! So be very careful, as using etc-update is significantly less safe than using dispatch-conf.
After merging the straightforward changes, you will be prompted with a list of protected files that have an update waiting. At the bottom you are greeted by the possible options:
If you enter -1, etc-update will exit and discontinue any further changes. If you enter -3 or -5, all listed configuration files will be overwritten with the newer versions. It is therefore very important to first select the configuration files that should not be automatically updated. This is simply a matter of entering the number listed to the left of that configuration file. As an example, we select the configuration file /etc/pear.conf:
You can now see the differences between the two files. If you believe that the updated configuration file can be used without problems, enter 1. If you believe that the updated configuration file isn't necessary, or doesn't provide any new or useful information, enter 2. If you want to interactively update your current configuration file, enter 3. There is no point in further elaborating the interactive merging here. For completeness sake, we will list the possible commands you can use while you are interactively merging the two files. You are greeted with two lines (the original one, and the proposed new one) and a prompt at which you can enter one of the following commands:
When you have finished updating the important configuration files, you can now automatically update all the other configuration files. etc-update will exit if it doesn't find any more updateable configuration files. With quickpkg you can create archives of the packages that are already merged on your system. These archives can be used as prebuilt packages. Running quickpkg is straightforward: just add the names of the packages you want to archive. For instance, to archive curl, orage, and procps:
The prebuilt packages will be stored in $PKGDIR (/usr/portage/packages/ by default). These packages are placed in $PKGDIR/<category>. 5. Diverting from the Official Tree5.a. Using a Portage Tree Subset You can selectively update certain categories/packages and ignore the other categories/packages. We achieve this by having rsync exclude categories/packages during the emerge --sync step. You need to define the name of the file that contains the exclude patterns in the PORTAGE_RSYNC_EXTRA_OPTS variable in your /etc/portage/make.conf.
Note however that this may lead to dependency issues since new, allowed packages might depend on new but excluded packages. 5.b. Adding Unofficial Ebuilds Defining a Portage Overlay Directory You can ask Portage to use ebuilds that are not officially available through the Portage tree. Create a new directory (for instance /usr/local/portage) in which you store the 3rd-party ebuilds. Use the same directory structure as the official Portage tree! Then define PORTDIR_OVERLAY in /etc/portage/make.conf and have it point to the previously defined directory. When you use Portage now, it will take those ebuilds into account as well without removing/overwriting those ebuilds the next time you run emerge --sync. For the powerusers who develop on several overlays, test packages before they hit the Portage tree or just want to use unofficial ebuilds from various sources, the app-portage/layman package brings you layman, a tool to help you keep the overlay repositories up to date. First install and configure layman as shown in the Overlays Users' Guide, and add your desired repositories with layman -a <overlay-name>. Suppose you have two repositories called java (for the in-development java ebuilds) and entapps (for the applications developed in-house for your enterprise). You can update those repositories with the following command:
For more information on working with overlays, please read man layman and the layman/overlay users' guide. 5.c. Non-Portage Maintained Software Using Portage with Self-Maintained Software In some cases you want to configure, install and maintain software yourself without having Portage automate the process for you, even though Portage can provide the software titles. Known cases are kernel sources and nvidia drivers. You can configure Portage so it knows that a certain package is manually installed on your system. This process is called injecting and supported by Portage through the /etc/portage/profile/package.provided file. For instance, if you want to inform Portage about gentoo-sources-2.6.11.6 which you've installed manually, add the following line to /etc/portage/profile/package.provided:
6. Advanced Portage FeaturesFor most users, the information received thus far is sufficient for all their Linux operations. But Portage is capable of much more; many of its features are for advanced users or only applicable in specific corner cases. Still, that would not be an excuse not to document them. Of course, with lots of flexibility comes a huge list of potential cases. It will not be possible to document them all here. Instead, we hope to focus on some generic issues which you can then bend to fit your own needs. If you have need for more specific tweaks and tips, you might find them on the Gentoo Wiki instead. Most, if not all of these additional features can be easily found by digging through the manual pages that portage provides:
Finally, know that these are advanced features which, if not worked with correctly, can make debugging and troubleshooting very difficult. Make sure you mention these if you think you hit a bug and want to open a bugreport. 6.b. Per-Package Environment Variables By default, package builds will use the environment variables defined in /etc/portage/make.conf, such as CFLAGS, MAKEOPTS and more. In some cases though, you might want to provide different variables for specific packages. To do so, Portage supports the use of /etc/portage/env and /etc/portage/package.env. The /etc/portage/package.env file contains the list of packages for which you want deviating variables as well as a specific identifier that tells Portage which changes you want. The identifier name you pick yourself, Portage will look for the variables in the /etc/portage/env/<identifier> file. Example: Using debugging for specific packages As an example, we enable debugging for the media-video/mplayer package. First of all, we set the debugging variables in a file called /etc/portage/env/debug-cflags. The name is arbitrarily chosen, but of course reflects the reason of the deviation to make it more obvious later why a deviation was put in.
Next, we tag the media-video/mplayer package to use this content:
6.c. Hooking In the Emerge Process Using /etc/portage/bashrc and affiliated files When Portage works with ebuilds, it uses a bash environment in which it calls the various build functions (like src_prepare, src_configure, pkg_postinst, etc.). But Portage also allows you to set up a bash environment yourself. The advantage of using your own bash environment is that you can hook in the emerge process during each step it performs. This can be done for every emerge (through /etc/portage/bashrc) or by using per-package environments (through /etc/portage/env as discussed earlier). To hook in the process, the bash environment can listen to the variables EBUILD_PHASE, CATEGORY as well as the variables that are always available during ebuild development (such as P, PF, ...). Based on the values of these variables, you can then execute additional steps. Example: Updating File Databases In this example, we'll use /etc/portage/bashrc to call some file database applications to ensure their databases are up to date with the system. The applications used in the example are aide (an intrusion detection tool) and updatedb (to use with locate), but these are meant as examples. Do not consider this as a HOWTO for AIDE ;-) To use /etc/portage/bashrc for this case, we need to "hook" in the postrm (after removal of files) and postinst (after installation of files) functions, because that is when the files on the file system have been changed.
6.d. Executing Tasks After --sync The /etc/portage/postsync.d location Until now we've talked about hooking into the ebuild processes. However, Portage also has another important function: updating the Portage tree. In order to run tasks after updating the Portage tree, put a script inside /etc/portage/postsync.d and make sure it is marked as executable. If you didn't use eix-sync to update the tree, you can still have its database updated after running emerge --sync (or emerge-webrsync) by putting a symlink to /usr/bin/eix called eix-update in /etc/portage/postsync.d.
6.e. Overriding Profile Settings The /etc/portage/profile location By default, Gentoo uses the settings contained in the profile pointed to by /etc/portage/make.profile (a symbolic link to the right profile directory). These profiles define both specific settings as well as inherit settings from other profiles (through their parent file). By using /etc/portage/profile, you can override profile settings such as packages (what packages are considered to be part of the system set), forced use flags and more. Example: Adding nfs-utils to the System Set If you use NFS-based file systems for rather critical file systems, you might want to have net-fs/nfs-utils "protected" as a system package, causing Portage to heavily warn you if it would be deleted. To accomplish that, we add the package to /etc/portage/profile/packages, prepended with a *:
6.f. Applying Non-Standard Patches To manage several ebuilds in a similar manner, ebuild developers use eclasses (sort-of shell libraries) that define commonly used functions. One of these eclasses is eutils.eclass which offers an interesting function called epatch_user. The epatch_user function applies source code patches that are found in /etc/portage/patches/<category>/<package>[-<version>[-<revision>]], whatever directory is found first. Sadly, not all ebuilds automatically call this function so just putting your patch in this location might not always work. Luckily, with the information provided above, you can call this function by hooking into, for instance, the prepare phase. The function can be called as many times as you like - it will only apply the patches once. Example: Applying Patches to Firefox The www-client/firefox package is one of the few that already call epatch_user from within the ebuild, so you do not need to override anything specific. If you need to patch firefox (for instance because a developer provided you with a patch and asked you to check if it fixes the bug you reported), put the patch in /etc/portage/patches/www-client/firefox (probably best to use the full name, including version so that the patch does not interfere with later versions) and rebuild firefox. D. Gentoo Network Configuration1. Getting Started
To get started configuring your network card, you need to tell the Gentoo RC system about it. This is done by creating a symbolic link from net.lo to net.eth0 (or whatever the network interface name is on your system) in /etc/init.d.
Gentoo's RC system now knows about that interface. It also needs to know how to configure the new interface. All the network interfaces are configured in /etc/conf.d/net. Below is a sample configuration for DHCP and static addresses.
Now that we have configured our interface, we can start and stop it using the following commands:
Now that you have successfully started and stopped your network interface, you may wish to get it to start when Gentoo boots. Here's how to do this. The last "rc" command instructs Gentoo to start any scripts in the current runlevel that have not yet been started.
2. Advanced ConfigurationThe config_eth0 variable is the heart of an interface configuration. It's a high level instruction list for configuring the interface (eth0 in this case). Each command in the instruction list is performed sequentially. The interface is deemed OK if at least one command works. Here's a list of built-in instructions.
If a command fails, you can specify a fallback command. The fallback has to match the config structure exactly. You can chain these commands together. Here are some real world examples.
Init scripts in /etc/init.d can depend on a specific network interface or just net. All network interfaces in Gentoo's init system provide what is called net. If, in /etc/rc.conf, rc_depend_strict="YES" is set, then all network interfaces that provide net must be active before a dependency on "net" is assumed to be met. In other words, if you have a net.eth0 and net.eth1 and an init script depends on "net", then both must be enabled. On the other hand, if rc_depend_strict="NO" is set, then the "net" dependency is marked as resolved the moment at least one network interface is brought up. But what about net.br0 depending on net.eth0 and net.eth1? net.eth1 may be a wireless or PPP device that needs configuration before it can be added to the bridge. This cannot be done in /etc/init.d/net.br0 as that's a symbolic link to net.lo. The answer is defining an rc_need_ setting in /etc/conf.d/net.
That alone, however, is not sufficient. Gentoo's networking init scripts use a virtual dependency called net to inform the system when networking is available. Clearly, in the above case, networking should only be marked as available when net.br0 is up, not when the others are. So we need to tell that in /etc/conf.d/net as well:
For a more detailed discussion about dependency, consult the section Writing Init Scripts in the Gentoo Handbook. More information about /etc/rc.conf is available as comments within that file. 2.c. Variable names and values Variable names are dynamic. They normally follow the structure of variable_${interface|mac|essid|apmac}. For example, the variable dhcpcd_eth0 holds the value for dhcpcd options for eth0 and dhcpcd_essid holds the value for dhcpcd options when any interface connects to the ESSID "essid". However, there is no hard and fast rule that states interface names must be ethx. In fact, many wireless interfaces have names like wlanx, rax as well as ethx. Also, some user defined interfaces such as bridges can be given any name, such as foo. To make life more interesting, wireless Access Points can have names with non alpha-numeric characters in them - this is important because you can configure networking parameters per ESSID. The downside of all this is that Gentoo uses bash variables for networking - and bash cannot use anything outside of English alpha-numerics. To get around this limitation we change every character that is not an English alpha-numeric into a _ character. Another downside of bash is the content of variables - some characters need to be escaped. This can be achived by placing the \ character in front of the character that needs to be escaped. The following list of characters needs to be escaped in this way: ", ' and \. In this example we use wireless ESSID as they can contain the widest scope of characters. We shall use the ESSID My "\ NET:
Network interface names are not chosen arbitrarily: the Linux kernel and the device manager (most sytems have udev as their device manager although others are available as well) choose the interface name through a fixed set of rules. When an interface card is detected on a system, the Linux kernel gathers the necessary data about this card. This includes:
Based on this information, the device manager decides how to name the interface on the system. By default, it uses the first hit of the above three parameters. For instance, if ID_NET_NAME_ONBOARD is found and set to eno1, then the interface will be called eno1. If you know your interface name, you can see the values of the provided parameters using udevadm:
As the first (and actually only) hit of the top three parameters is the ID_NET_NAME_PATH one, its value is used as the interface name. If none of the parameters is found, then the system reverts back to the kernel-provided naming (eth0, eth1, etc.) Using the Old-style Kernel Naming Before this change, network interface cards were named by the Linux kernel itself, depending on the order that drivers are loaded (amongst other, possibly more obscure reasons). This behavior can still be enabled by setting the net.ifnames=0 boot option in the boot loader. Another way of disabling this behavior (and thus reverting back to the kernel-provided naming) is to create an empty udev rule named 80-net-name-slot.rules which will then override the default provided one (with the same name) that is responsible for taking care of network interface naming.
The entire idea behind the change in naming is not to confuse people, but to make changing the names easier. Suppose you have two interfaces that are otherwise called eth0 and eth1. One is meant to access the network through a wire, the other one is for wireless access. With the support for interface naming, you can have these called lan0 (wired) and wifi0 (wireless - it is best to avoid using the previously well-known names like eth* and wlan* as those can still collide with your suggested names). All you need to do is to find out what the parameters are for the cards and then use this information to set up your own naming rule:
Because the rules are triggered before the default one (rules are triggered in alphanumerical order, so 70 comes before 80) the names provided in the rule file will be used instead of the default ones. The number granted to the file should be between 76 and 79 (the environment variables are defined by a rule start starts with 75 and the fallback naming is done in a rule numbered 80). 3. Modular NetworkingWe now support modular networking scripts, which means we can easily add support for new interface types and configuration modules while keeping compatibility with existing ones. Modules load by default if the package they need is installed. If you specify a module here that doesn't have its package installed then you get an error stating which package you need to install. Ideally, you only use the modules setting when you have two or more packages installed that supply the same service and you need to prefer one over the other.
We provide two interface handlers presently: ifconfig and iproute2. You need one of these to do any kind of network configuration. ifconfig is installed by default (the net-tools package is part of the system profile). iproute2 is a more powerful and flexible package, but it's not included by default.
As both ifconfig and iproute2 do very similar things we allow their basic configuration to work with each other. For example both the below code snippet work regardless of which module you are using.
DHCP is a means of obtaining network information (IP address, DNS servers, Gateway, etc) from a DHCP server. This means that if there is a DHCP server running on the network, you just have to tell each client to use DHCP and it sets up the network all by itself. Of course, you will have to configure for other things like wireless, PPP or other things if required before you can use DHCP. DHCP can be provided by dhclient, dhcpcd, or pump. Each DHCP module has its pros and cons - here's a quick run down.
If you have more than one DHCP client installed, you need to specify which one to use - otherwise we default to dhcpcd if available. To send specific options to the DHCP module, use module_eth0="..." (change module to the DHCP module you're using - i.e. dhcpcd_eth0). We try and make DHCP relatively agnostic - as such we support the following commands using the dhcp_eth0 variable. The default is not to set any of them:
First we need to install the ADSL software.
Second, create the PPP net script and the net script for the ethernet interface to be used by PPP:
Be sure to set rc_depend_strict to "YES" in /etc/rc.conf. Now we need to configure /etc/conf.d/net.
You can also set your password in /etc/ppp/pap-secrets.
If you use PPPoE with a USB modem you'll need to emerge br2684ctl. Please read /usr/portage/net-dialup/speedtouch-usb/files/README for information on how to properly configure it.
3.e. APIPA (Automatic Private IP Addressing) APIPA tries to find a free address in the range 169.254.0.0-169.254.255.255 by arping a random address in that range on the interface. If no reply is found then we assign that address to the interface. This is only useful for LANs where there is no DHCP server and you don't connect directly to the internet and all other computers use APIPA. For APIPA support, emerge net-misc/iputils or net-analyzer/arping.
For link bonding/trunking emerge net-misc/ifenslave. Bonding is used to increase network bandwidth. If you have two network cards going to the same network, you can bond them together so your applications see just one interface but they really use both network cards.
3.g. Bridging (802.1d support) For bridging support emerge net-misc/bridge-utils. Bridging is used to join networks together. For example, you may have a server that connects to the internet via an ADSL modem and a wireless access card to enable other computers to connect to the internet via the ADSL modem. You could create a bridge to join the two interfaces together.
If you need to, you can change the MAC address of your interfaces through the network configuration file too.
You don't need to emerge anything for tunnelling as the interface handler can do it for you.
For VLAN support, emerge net-misc/vconfig. Virtual LAN is a group of network devices that behave as if they were connected to a single network segment - even though they may not be. VLAN members can only see members of the same VLAN even though they may share the same physical network.
4. Wireless NetworkingWireless networking on Linux is usually pretty straightforward. There are two ways of configuring wifi: graphical clients, or the command line. The easiest way is to use a graphical client once you've installed a desktop environment. Most graphical clients, such as wicd and NetworkManager, are pretty self-explanatory. They offer a handy point-and-click interface that gets you on a network in just a few seconds.
However, if you don't want to use a graphical client, then you can configure wifi on the command line by editing a few configuration files. This takes a bit more time to setup, but it also requires the fewest packages to download and install. Since the graphical clients are mostly self-explanatory (with helpful screenshots at their homepages), we'll focus on the command line alternatives. You can setup wireless networking on the command line by installing wireless-tools or wpa_supplicant. The important thing to remember is that you configure wireless networks on a global basis and not an interface basis. wpa_supplicant is the best choice. For a list of supported drivers, read the wpa_supplicant site. wireless-tools supports nearly all cards and drivers, but it cannot connect to WPA-only Access Points. If your networks only offer WEP encryption or are completely open, you may prefer the simplicity of wireless-tools.
WPA Supplicant is a package that allows you to connect to WPA enabled access points.
Now we have to configure /etc/conf.d/net to so that we prefer wpa_supplicant over wireless-tools (if both are installed, wireless-tools is the default).
That was simple, wasn't it? However, we still have to configure wpa_supplicant itself which is a bit more tricky depending on how secure the Access Points are that you are trying to connect to. The below example is taken and simplified from /usr/share/doc/wpa_supplicant-<version>/wpa_supplicant.conf.gz which ships with wpa_supplicant.
Initial setup and Managed Mode Wireless Tools provide a generic way to configure basic wireless interfaces up to the WEP security level. While WEP is a weak security method it's also the most prevalent. Wireless Tools configuration is controlled by a few main variables. The sample configuration file below should describe all you need. One thing to bear in mind is that no configuration means "connect to the strongest unencrypted Access Point" - we will always try and connect you to something.
Fine tune Access Point Selection You can add some extra options to fine-tune your Access Point selection, but these are not normally required. You can decide whether we only connect to preferred Access Points or not. By default if everything configured has failed and we can connect to an unencrypted Access Point then we will. This can be controlled by the associate_order variable. Here's a table of values and how they control this.
Finally we have some blacklist_aps and unique_ap selection. blacklist_aps works in a similar way to preferred_aps. unique_ap is a yes or no value that says if a second wireless interface can connect to the same Access Point as the first interface.
If you want to set yourself up as an Ad-Hoc node if you fail to connect to any Access Point in managed mode, you can do that too.
What about connecting to Ad-Hoc networks or running in Master mode to become an Access Point? Here's a configuration just for that! You may need to specify WEP keys as shown above.
Troubleshooting Wireless Tools There are some more variables you can use to help get your wireless up and running due to driver or environment problems. Here's a table of other things you can try.
4.d. Defining network configuration per ESSID Sometimes, you need a static IP when you connect to ESSID1 and you need DHCP when you connect to ESSID2. In fact, most module variables can be defined per ESSID. Here's how we do this.
5. Adding FunctionalityFour functions can be defined in /etc/conf.d/net which will be called surrounding the start/stop operations. The functions are called with the interface name first so that one function can control multiple adapters. The return values for the preup() and predown() functions should be 0 (success) to indicate that configuration or deconfiguration of the interface can continue. If preup() returns a non-zero value, then interface configuration will be aborted. If predown() returns a non-zero value, then the interface will not be allowed to continue deconfiguration. The return values for the postup() and postdown() functions are ignored since there's nothing to do if they indicate failure. ${IFACE} is set to the interface being brought up/down. ${IFVAR} is ${IFACE} converted to variable name bash allows.
5.b. Wireless Tools function hooks
Two functions can be defined in /etc/conf.d/net which will be called surrounding the associate function. The functions are called with the interface name first so that one function can control multiple adapters. The return values for the preassociate() function should be 0 (success) to indicate that configuration or deconfiguration of the interface can continue. If preassociate() returns a non-zero value, then interface configuration will be aborted. The return value for the postassociate() function is ignored since there's nothing to do if it indicates failure. ${ESSID} is set to the exact ESSID of the AP you're connecting to. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.
6. Network ManagementIf you and your computer are always on the move, you may not always have an ethernet cable or plugged in or an access point available. Also, you may want networking to automatically work when an ethernet cable is plugged in or an access point is found. Here you can find some tools that help you manage this.
ifplugd is a daemon that starts and stops interfaces when an ethernet cable is inserted or removed. It can also manage detecting association to Access Points or when new ones come in range.
Configuration for ifplugd is fairly straightforward too. The configuration file is held in /etc/conf.d/net. Run man ifplugd for details on the available variables. Also, see /usr/share/doc/openrc-*/net.example.bz2 for more examples.
In addition to managing multiple network connections, you may want to add a tool that makes it easy to work with multiple DNS servers and configurations. This is very handy when you receive your IP address via DHCP. Simply emerge openresolv.
See man resolvconf to learn more about its features. The contents of this document, unless otherwise expressly stated, are licensed under the CC-BY-SA-2.5 license. The Gentoo Name and Logo Usage Guidelines apply. |
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