4.4. Configurer l'environnement
Configurez un bon environnement de travail en créant deux nouveaux
fichiers de démarrage pour le shell bash. En étant connecté en tant
qu'utilisateur lfs, lancez la
commande suivante pour créer un nouveau .bash_profile :
cat > ~/.bash_profile << "EOF"
exec env -i HOME=$HOME TERM=$TERM PS1='\u:\w\$ ' /bin/bash
EOF
When logged on as user lfs, or when
switched to the lfs user using an
su command with the
« - » option, the
initial shell is a login shell
which reads the /etc/profile of the
host (probably containing some settings and environment variables)
and then .bash_profile. The
exec env -i.../bin/bash
command in the .bash_profile file
replaces the running shell with a new one with a completely empty
environment, except for the HOME,
TERM, and PS1
variables. This ensures that no unwanted and potentially hazardous
environment variables from the host system leak into the build
environment.
The new instance of the shell is a non-login shell, which does not read, and
execute, the contents of the /etc/profile or .bash_profile files, but rather reads, and
executes, the .bashrc file instead.
Create the .bashrc file now:
cat > ~/.bashrc << "EOF"
set +h
umask 022
LFS=/mnt/lfs
LC_ALL=POSIX
LFS_TGT=$(uname -m)-lfs-linux-gnu
PATH=/usr/bin
if [ ! -L /bin ]; then PATH=/bin:$PATH; fi
PATH=$LFS/tools/bin:$PATH
CONFIG_SITE=$LFS/usr/share/config.site
export LFS LC_ALL LFS_TGT PATH CONFIG_SITE
EOF
Voici la signification des paramètres dans .bashrc
-
set +h -
The set +h command turns off bash's hash function. Hashing is ordinarily a useful feature—bash uses a hash table to remember the full path to executable files to avoid searching the
PATHtime and again to find the same executable. However, the new tools should be used as soon as they are installed. Switching off the hash function forces the shell to search thePATHwhenever a program is to be run. As such, the shell will find the newly compiled tools in$LFS/tools/binas soon as they are available without remembering a previous version of the same program provided by the host distro, in/usr/binor/bin. -
umask 022 -
Configurer le masque de création de fichier (umask) à 022 nous assure que les nouveaux fichiers et répertoires créés sont modifiables uniquement par leurs propriétaires mais lisibles et exécutables par tout le monde (en supposant que l'appel système
open(2)utilise les modes par défaut, les nouveaux fichiers finiront avec les droits 644 et les répertoires avec les droits 755). -
LFS=/mnt/lfs -
La variable
LFSdevrait être configurée avec le point de montage choisi. -
LC_ALL=POSIX -
The
LC_ALLvariable controls the localization of certain programs, making their messages follow the conventions of a specified country. SettingLC_ALLto « POSIX » or « C » (the two are equivalent) ensures that everything will work as expected in the cross-compilation environment. -
LFS_TGT=(uname -m)-lfs-linux-gnu -
The
LFS_TGTvariable sets a non-default, but compatible machine description for use when building our cross-compiler and linker and when cross-compiling our temporary toolchain. More information is provided by Notes techniques sur la chaîne d'outils. -
PATH=/usr/bin -
Many modern Linux distributions have merged
/binand/usr/bin. When this is the case, the standardPATHvariable should be set to/usr/bin/for the Chapitre 6 environment. When this is not the case, the following line adds/binto the path. -
if [ ! -L /bin ]; then PATH=/bin:$PATH; fi -
If
/binis not a symbolic link, it must be added to thePATHvariable. -
PATH=$LFS/tools/bin:$PATH -
By putting
$LFS/tools/binahead of the standardPATH, the cross-compiler installed at the beginning of Chapitre 5 is picked up by the shell immediately after its installation. This, combined with turning off hashing, limits the risk that the compiler from the host is used instead of the cross-compiler. -
CONFIG_SITE=$LFS/usr/share/config.site -
Dans le Chapitre 5 et le Chapitre 6, si cette variable n'est pas initialisée, les scripts configure peuvent essayer de charger des bouts de configuration de certaines distributions dans
/usr/share/config.sitesur le système hôte. Changer ce chemin permet d'éviter une contamination potentielle par l'hôte. -
export ... -
While the preceding commands have set some variables, in order to make them visible within any sub-shells, we export them.
![[Important]](../images/important.png)
Important
Several commercial distributions add an undocumented instantiation
of /etc/bash.bashrc to the
initialization of bash. This file has the potential
to modify the lfs user's
environment in ways that can affect the building of critical LFS
packages. To make sure the lfs
user's environment is clean, check for the presence of /etc/bash.bashrc and, if present, move it out of
the way. As the root user, run:
[ ! -e /etc/bash.bashrc ] || mv -v /etc/bash.bashrc /etc/bash.bashrc.NOUSE
When the lfs user is no longer
needed (at the beginning of
Chapitre 7), you may safely restore /etc/bash.bashrc (if desired).
Remarquez que le paquet Bash de LFS que nous construisons dans la
Section 8.34, « Bash-5.2 »
n'est pas configuré pour charger ou exécuter /etc/bash.bashrc, donc ce fichier est inutile sur
un système LFS.
Finally, to ensure the environment is fully prepared for building the temporary tools, force the bash shell to read the new user profile:
source ~/.bash_profile