website annotate en/doc/handbook/chroot-env.html @ rev 156

en: Tidy website grammar
author Paul Issott <paul@slitaz.org>
date Tue Sep 09 10:36:54 2008 +0000 (2008-09-09)
parents 9e30e64c8198
children fa2c5bed2417
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paul@68 5 <title>SliTaz Handbook (en) - Chroot environment</title>
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paul@41 24 <h1><font color="#3e1220">SliTaz Handbook (en)</font></h1>
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paul@41 30
paul@41 31 <h2><font color="#df8f06">Chroot environment</font></h2>
paul@41 32
paul@41 33 <p>
paul@41 34 This document describes the necessary steps to create a chrooted environment, in order to change the root
paul@41 35 of the system so that you can work. This makes it possible to compile, test and develop SliTaz without any risk to
paul@41 36 the host system you're working on. The host system can be SliTaz installed to a hard drive or any other GNU/Linux system
paul@41 37 such as Debian, Fedora, PCLinuxOS and so on. You can also create a chrooted environment in LiveCD mode
paul@41 38 associated with USB media. The only prerequisite is to have a SliTaz ISO image available and a little
paul@41 39 time. Note that all commands are carried out as system administrator (<em>root</em>).
paul@41 40 </p>
paul@41 41 <h3>Prepare the environment</h3>
paul@41 42 <p>
paul@41 43 To begin, we must extract the contents of the ISO image into the directory that will serve as our chroot.
paul@41 44 The directory can be created any place you choose, we'll use a directory <code>/home/slitaz/chroot-env</code>.
paul@41 45 To extract the contents of an ISO image, we must mount it in a <em>loop</em> directory and then copy the compressed
paul@41 46 root filesystem (<code>rootfs.gz</code>) into the chroot directory. Assuming the ISO is in the current directory:
paul@41 47 </p>
paul@41 48 <pre> # mkdir /tmp/loop
paul@41 49 # mount -o loop slitaz-cooking.iso /tmp/loop
paul@41 50 # mkdir -p /home/slitaz/chroot-env
paul@41 51 # cp /tmp/loop/boot/rootfs.gz \
paul@41 52 /home/slitaz/chroot-env
paul@41 53 # umount /tmp/loop
paul@41 54 </pre>
paul@41 55 <p>
paul@41 56 Now we have a copy of the compressed filesystem, we must extract and unpack it (this is a <code>cpio</code>
paul@41 57 archive compressed with either gzip or lzma). To complete this stage, we can remove the
paul@41 58 <code>rootfs</code> which is no longer required:
paul@41 59 </p>
paul@41 60 <pre> # cd /home/slitaz/chroot-env
paul@41 61 # (zcat rootfs.gz 2&gt;/dev/null || lzma d rootfs.gz -so) | cpio -id
paul@41 62 # rm rootfs rootfs.gz
paul@41 63 </pre>
paul@41 64 <p>
paul@41 65 If the unpacking of the rootfs compressed with lzma fails; you can use the following method:
paul@41 66 </p>
paul@41 67 <pre> # unlzma rootfs.gz -S .gz
paul@41 68 # cat rootfs | cpio -id
paul@41 69 </pre>
paul@41 70
paul@41 71 <h3>Using the environment</h3>
paul@41 72 <p>
paul@41 73 To begin using the chrooted environment, you just need to mount some virtual filesystems and use the <code>chroot</code>
paul@41 74 command. To simplify things, we can write a small script automating the process. Example using the
paul@41 75 chroot directory <code>/home/slitaz/chroot-env</code> and creating a script
paul@41 76 <code>chroot_in_env.sh</code> in <code>/home/slitaz</code>.
paul@41 77 On any systems other than SliTaz you can uncomment the lines about <code>/dev</code> and
paul@41 78 <code>/tmp</code> - <em>Note</em> to save typing you can copy and paste:
paul@41 79 </p>
paul@41 80 <pre> # cat &gt; /home/slitaz/chroot_in_env.sh &lt;&lt; "EOF"
paul@41 81 </pre>
paul@41 82 <pre class="script">#!/bin/sh
paul@41 83 # Chroot in SliTaz to hack.
paul@41 84 #
paul@41 85 ROOTFS="/home/slitaz/chroot-env"
paul@41 86
paul@41 87 # Mount virtual Kernel file systems and chroot.
paul@41 88 #
paul@41 89 #mount --bind /dev $ROOTFS/dev
paul@41 90 #mount --bind /tmp $ROOTFS/tmp
paul@41 91 mount -t proc proc $ROOTFS/proc
paul@41 92 mount -t sysfs sysfs $ROOTFS/sys
paul@41 93 mount -t devpts devpts $ROOTFS/dev/pts
paul@41 94 mount -t tmpfs shm $ROOTFS/dev/shm
paul@41 95
MikeDSmith25@117 96 echo "Chrooting into $ROOTFS... "
paul@41 97 chroot $ROOTFS /bin/sh --login
paul@41 98
paul@41 99 # Unmount virtual Kernel file systems on exit.
paul@41 100 #
paul@41 101 umount $ROOTFS/dev/shm
paul@41 102 umount $ROOTFS/dev/pts
paul@41 103 umount $ROOTFS/sys
paul@41 104 umount $ROOTFS/proc
paul@41 105 #umount $ROOTFS/tmp
paul@41 106 #umount $ROOTFS/dev
paul@41 107
MikeDSmith25@117 108 echo "Exiting $ROOTFS chroot environment... "
paul@41 109
paul@41 110 EOF
paul@41 111 </pre>
paul@41 112 <p>
paul@41 113 To finish and test the environment, you just make the script executable and run:
paul@41 114 </p>
paul@41 115 <pre> # chmod +x /home/slitaz/chroot_in_env.sh
paul@41 116 # sh /home/slitaz/chroot_in_env.sh
paul@41 117 </pre>
paul@41 118 <h4>To activate the network</h4>
paul@41 119 <p>
paul@41 120 In order to have the network up to download and install some development packages, just start the
paul@41 121 DHCP client on the correct interface. Example using <code>eth1</code>:
paul@41 122 </p>
paul@41 123 <pre> /# udhcpc -i eth1
paul@41 124 </pre>
paul@41 125 <h4>Installing packages</h4>
paul@41 126 <p>
paul@41 127 If the network is functional, just reload the list of packages and use <code>tazpkg get-install</code> to
paul@41 128 install them. If a connection is not possible, you can download the packages from another system, copy them
paul@41 129 to the chrooted environment and install them with the <code>tazpkg install</code> command. To install the basic
paul@41 130 compilation tools:
paul@41 131 </p>
paul@41 132 <pre> /# tazpkg recharge
paul@41 133 /# tazpkg get-install slitaz-toolchain
paul@41 134 </pre>
paul@41 135 <p>
paul@156 136 Once the environment is configured, you can compile applications from source to create packages, test scripts, etc.
paul@41 137 The <a href="../cookbook/">Cookbook</a> should help you out here:
paul@41 138 </p>
paul@41 139 <h4>Exit the environment</h4>
paul@41 140 <p>
paul@41 141 To exit the chrooted environment, just type <code>exit</code>, the <code>chroot_in_env.sh</code> script will then end
paul@41 142 by unmounting the virtual filesystems from the Linux Kernel:
paul@41 143 </p>
paul@41 144 <pre> /# exit
paul@41 145 #
paul@41 146 </pre>
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