[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
|
---|
[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
---|
| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
|
---|
[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
|
---|
| 5 | %general-entities;
|
---|
| 6 | ]>
|
---|
[6a3b6af] | 7 |
|
---|
[afcfd74] | 8 | <sect1 id="ch-preps-settingenviron">
|
---|
[6a3b6af] | 9 | <?dbhtml filename="settingenvironment.html"?>
|
---|
| 10 |
|
---|
| 11 | <title>Setting Up the Environment</title>
|
---|
[673b0d8] | 12 |
|
---|
[6a3b6af] | 13 | <para>Set up a good working environment by creating two new startup files
|
---|
| 14 | for the <command>bash</command> shell. While logged in as user
|
---|
| 15 | <systemitem class="username">lfs</systemitem>, issue the following command
|
---|
| 16 | to create a new <filename>.bash_profile</filename>:</para>
|
---|
[81fd230] | 17 |
|
---|
[05616e2] | 18 | <screen><userinput>cat > ~/.bash_profile << "EOF"
|
---|
[d72e04a] | 19 | <literal>exec env -i HOME=$HOME TERM=$TERM PS1='\u:\w\$ ' /bin/bash</literal>
|
---|
[55851d6] | 20 | EOF</userinput></screen>
|
---|
[673b0d8] | 21 |
|
---|
[6a3b6af] | 22 | <para>When logged on as user <systemitem class="username">lfs</systemitem>,
|
---|
| 23 | the initial shell is usually a <emphasis>login</emphasis> shell which reads
|
---|
| 24 | the <filename>/etc/profile</filename> of the host (probably containing some
|
---|
| 25 | settings and environment variables) and then <filename>.bash_profile</filename>.
|
---|
| 26 | The <command>exec env -i.../bin/bash</command> command in the
|
---|
| 27 | <filename>.bash_profile</filename> file replaces the running shell with a new
|
---|
| 28 | one with a completely empty environment, except for the <envar>HOME</envar>,
|
---|
| 29 | <envar>TERM</envar>, and <envar>PS1</envar> variables. This ensures that no
|
---|
| 30 | unwanted and potentially hazardous environment variables from the host system
|
---|
| 31 | leak into the build environment. The technique used here achieves the goal of
|
---|
| 32 | ensuring a clean environment.</para>
|
---|
[81fd230] | 33 |
|
---|
[6a3b6af] | 34 | <para>The new instance of the shell is a <emphasis>non-login</emphasis>
|
---|
[6a06eaf] | 35 | shell, which does not read, and execute, the contents of <filename>/etc/profile</filename> or
|
---|
[df43be1] | 36 | <filename>.bash_profile</filename> files, but rather reads, and executes, the
|
---|
[6a3b6af] | 37 | <filename>.bashrc</filename> file instead. Create the
|
---|
| 38 | <filename>.bashrc</filename> file now:</para>
|
---|
[81fd230] | 39 |
|
---|
[05616e2] | 40 | <screen><userinput>cat > ~/.bashrc << "EOF"
|
---|
[d72e04a] | 41 | <literal>set +h
|
---|
[673b0d8] | 42 | umask 022
|
---|
| 43 | LFS=/mnt/lfs
|
---|
| 44 | LC_ALL=POSIX
|
---|
[4e82d47] | 45 | LFS_TGT=$(uname -m)-lfs-linux-gnu
|
---|
[b454589] | 46 | PATH=/usr/bin
|
---|
[a97aa3d] | 47 | if [ ! -L /bin ]; then PATH=/bin:$PATH; fi
|
---|
[b454589] | 48 | PATH=$LFS/tools/bin:$PATH
|
---|
[df77b24] | 49 | CONFIG_SITE=$LFS/usr/share/config.site
|
---|
| 50 | export LFS LC_ALL LFS_TGT PATH CONFIG_SITE</literal>
|
---|
[55851d6] | 51 | EOF</userinput></screen>
|
---|
[673b0d8] | 52 |
|
---|
[df43be1] | 53 | <variablelist>
|
---|
[ee714d3] | 54 | <title>The meaning of the settings in <filename>.bashrc</filename></title>
|
---|
[df43be1] | 55 |
|
---|
| 56 | <varlistentry>
|
---|
| 57 | <term><parameter>set +h</parameter></term>
|
---|
| 58 | <listitem>
|
---|
[6a3b6af] | 59 | <para>The <command>set +h</command> command turns off
|
---|
| 60 | <command>bash</command>'s hash function. Hashing is ordinarily a useful
|
---|
| 61 | feature—<command>bash</command> uses a hash table to remember the
|
---|
| 62 | full path of executable files to avoid searching the <envar>PATH</envar>
|
---|
| 63 | time and again to find the same executable. However, the new tools should
|
---|
| 64 | be used as soon as they are installed. By switching off the hash function,
|
---|
| 65 | the shell will always search the <envar>PATH</envar> when a program is to
|
---|
| 66 | be run. As such, the shell will find the newly compiled tools in
|
---|
[490dc153] | 67 | <filename class="directory">$LFS/tools/bin</filename> as soon as they are
|
---|
| 68 | available without remembering a previous version of the same program
|
---|
| 69 | provided by the host distro, in
|
---|
| 70 | <filename class='directory'>/usr/bin</filename> or
|
---|
| 71 | <filename class='directory'>/bin</filename>.</para>
|
---|
[df43be1] | 72 | </listitem>
|
---|
| 73 | </varlistentry>
|
---|
[81fd230] | 74 |
|
---|
[df43be1] | 75 | <varlistentry>
|
---|
| 76 | <term><parameter>umask 022</parameter></term>
|
---|
| 77 | <listitem>
|
---|
[6a3b6af] | 78 | <para>Setting the user file-creation mask (umask) to 022 ensures that newly
|
---|
| 79 | created files and directories are only writable by their owner, but are
|
---|
| 80 | readable and executable by anyone (assuming default modes are used by the
|
---|
| 81 | <function>open(2)</function> system call, new files will end up with permission
|
---|
| 82 | mode 644 and directories with mode 755).</para>
|
---|
[df43be1] | 83 | </listitem>
|
---|
| 84 | </varlistentry>
|
---|
[81fd230] | 85 |
|
---|
[df43be1] | 86 | <varlistentry>
|
---|
| 87 | <term><parameter>LFS=/mnt/lfs</parameter></term>
|
---|
| 88 | <listitem>
|
---|
[6a3b6af] | 89 | <para>The <envar>LFS</envar> variable should be set to the chosen mount
|
---|
| 90 | point.</para>
|
---|
[df43be1] | 91 | </listitem>
|
---|
| 92 | </varlistentry>
|
---|
[81fd230] | 93 |
|
---|
[df43be1] | 94 | <varlistentry>
|
---|
| 95 | <term><parameter>LC_ALL=POSIX</parameter></term>
|
---|
| 96 | <listitem>
|
---|
[6a3b6af] | 97 | <para>The <envar>LC_ALL</envar> variable controls the localization of certain
|
---|
| 98 | programs, making their messages follow the conventions of a specified country.
|
---|
[448e226] | 99 | Setting <envar>LC_ALL</envar> to <quote>POSIX</quote> or <quote>C</quote>
|
---|
| 100 | (the two are equivalent) ensures that everything will work as expected in
|
---|
| 101 | the chroot environment.</para>
|
---|
[df43be1] | 102 | </listitem>
|
---|
| 103 | </varlistentry>
|
---|
[81fd230] | 104 |
|
---|
[df43be1] | 105 | <varlistentry>
|
---|
| 106 | <term><parameter>LFS_TGT=(uname -m)-lfs-linux-gnu</parameter></term>
|
---|
| 107 | <listitem>
|
---|
[4e82d47] | 108 | <para>The <envar>LFS_TGT</envar> variable sets a non-default, but compatible machine
|
---|
| 109 | description for use when building our cross compiler and linker and when cross
|
---|
| 110 | compiling our temporary toolchain. More information is contained in
|
---|
| 111 | <xref linkend="ch-tools-toolchaintechnotes" role=""/>.</para>
|
---|
[df43be1] | 112 | </listitem>
|
---|
| 113 | </varlistentry>
|
---|
[4e82d47] | 114 |
|
---|
[df43be1] | 115 | <varlistentry>
|
---|
[b454589] | 116 | <term><parameter>PATH=/usr/bin</parameter></term>
|
---|
| 117 | <listitem>
|
---|
| 118 | <para>Many modern linux distributions have merged <filename
|
---|
| 119 | class="directory">/bin</filename> and <filename
|
---|
| 120 | class="directory">/usr/bin</filename>. When this is the case, the standard
|
---|
| 121 | <envar>PATH</envar> variable needs just to be set to <filename
|
---|
| 122 | class="directory">/usr/bin/</filename> for the <xref
|
---|
| 123 | linkend="chapter-temporary-tools"/> environment. When this is not the
|
---|
| 124 | case, the following line adds <filename class="directory">/bin</filename>
|
---|
| 125 | to the path.</para>
|
---|
| 126 | </listitem>
|
---|
| 127 | </varlistentry>
|
---|
| 128 |
|
---|
| 129 | <varlistentry>
|
---|
[a97aa3d] | 130 | <term><parameter>if [ ! -L /bin ]; then PATH=/bin:$PATH; fi</parameter></term>
|
---|
[b454589] | 131 | <listitem>
|
---|
| 132 | <para>If <filename class="directory">/bin</filename> is not a symbolic
|
---|
| 133 | link, then it has to be added to the <envar>PATH</envar> variable.</para>
|
---|
| 134 | </listitem>
|
---|
| 135 | </varlistentry>
|
---|
| 136 |
|
---|
| 137 | <varlistentry>
|
---|
| 138 | <term><parameter>PATH=$LFS/tools/bin:$PATH</parameter></term>
|
---|
[df43be1] | 139 | <listitem>
|
---|
[efcb393] | 140 | <para>By putting <filename class="directory">$LFS/tools/bin</filename> ahead of the
|
---|
[b454589] | 141 | standard <envar>PATH</envar>, the cross-compiler installed at the beginning
|
---|
[ee714d3] | 142 | of <xref linkend="chapter-cross-tools"/> is picked up by the shell
|
---|
[b454589] | 143 | immediately after its installation. This, combined with turning off hashing,
|
---|
| 144 | limits the risk that the compiler from the host be used instead of the
|
---|
| 145 | cross-compiler.</para>
|
---|
[df43be1] | 146 | </listitem>
|
---|
| 147 | </varlistentry>
|
---|
| 148 |
|
---|
| 149 | <varlistentry>
|
---|
[df77b24] | 150 | <term><parameter>CONFIG_SITE=$LFS/usr/share/config.site</parameter></term>
|
---|
| 151 | <listitem>
|
---|
| 152 | <para>In <xref linkend="chapter-cross-tools"/> and
|
---|
| 153 | <xref linkend="chapter-temporary-tools"/>, if this variable is not set,
|
---|
| 154 | <command>configure</command> scripts
|
---|
[a2d41cf2] | 155 | may attempt to load configuration items specific to some distributions from
|
---|
| 156 | <filename>/usr/share/config.site</filename> on the host system. Override
|
---|
| 157 | it to prevent potential contamination from the host.</para>
|
---|
[df77b24] | 158 | </listitem>
|
---|
| 159 | </varlistentry>
|
---|
| 160 |
|
---|
| 161 | <varlistentry>
|
---|
| 162 | <term><parameter>export ...</parameter></term>
|
---|
[df43be1] | 163 | <listitem>
|
---|
| 164 | <para>While the above commands have set some variables, in order
|
---|
[ee714d3] | 165 | to make them visible within any sub-shells, we export them.</para>
|
---|
[df43be1] | 166 | </listitem>
|
---|
| 167 | </varlistentry>
|
---|
| 168 |
|
---|
| 169 | </variablelist>
|
---|
[81fd230] | 170 |
|
---|
[686c88b] | 171 | <important>
|
---|
| 172 |
|
---|
| 173 | <para>Several commercial distributions add a non-documented instantiation
|
---|
| 174 | of <filename>/etc/bash.bashrc</filename> to the initialization of
|
---|
[3a38c46] | 175 | <command>bash</command>. This file has the potential to modify the
|
---|
| 176 | <systemitem class="username">lfs</systemitem>
|
---|
[dbb9122] | 177 | user's environment in ways that can affect the building of critical LFS
|
---|
[3a38c46] | 178 | packages. To make sure the <systemitem class="username">lfs</systemitem>
|
---|
[c0c616a] | 179 | user's environment is clean, check for the
|
---|
[686c88b] | 180 | presence of <filename>/etc/bash.bashrc</filename> and, if present, move it
|
---|
[3a38c46] | 181 | out of the way. As the <systemitem class="username">root</systemitem>
|
---|
| 182 | user, run:</para>
|
---|
[686c88b] | 183 |
|
---|
[707c4d3] | 184 | <screen role="nodump"><userinput>[ ! -e /etc/bash.bashrc ] || mv -v /etc/bash.bashrc /etc/bash.bashrc.NOUSE</userinput></screen>
|
---|
[686c88b] | 185 |
|
---|
[ee0638f] | 186 | <para>After use of the <systemitem class="username">lfs</systemitem>
|
---|
| 187 | user is finished at the beginning of <xref
|
---|
[686c88b] | 188 | linkend="chapter-chroot-temporary-tools"/>, you can restore
|
---|
[3a38c46] | 189 | <filename>/etc/bash.bashrc</filename> (if desired).</para>
|
---|
| 190 |
|
---|
| 191 | <para>Note that the LFS Bash package we will build in
|
---|
| 192 | <xref linkend="ch-system-bash"/> is not configured to load or execute
|
---|
| 193 | <filename>/etc/bash.bashrc</filename>, so this file is useless on a
|
---|
| 194 | completed LFS system.</para>
|
---|
[686c88b] | 195 | </important>
|
---|
| 196 |
|
---|
[6a3b6af] | 197 | <para>Finally, to have the environment fully prepared for building the
|
---|
| 198 | temporary tools, source the just-created user profile:</para>
|
---|
[81fd230] | 199 |
|
---|
[673b0d8] | 200 | <screen><userinput>source ~/.bash_profile</userinput></screen>
|
---|
| 201 |
|
---|
| 202 | </sect1>
|
---|