export ${CLFS}=/mnt/clfs
To ensure a clean separation between host and build environments we will create a custom .bashrc file. This file will be read when invoking a non-login instance of bash.
The new instance of the shell is a non-login shell, which does not read the
/etc/profile or .bash_profile files, but rather reads the
.bashrc file instead. Create the
.bashrc file now:
cat > ${CLFS}/.bashrc << "EOF"
set +h
umask 022
CLFS=/mnt/clfs
HOME=/mnt/clfs
PS1='clfs-\u:\w\$ '
LC_ALL=POSIX
PATH=${CLFS}/cross-tools/bin:/bin:/usr/bin
export CLFS LC_ALL PATH
EOF
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 of executable files to avoid searching the PATH time and again to find the same executable.
However, the new tools should be used as soon as they are installed.
By switching off the hash function, the shell will always search the
PATH when a program is to be run. As such,
the shell will find the newly compiled tools in ${CLFS}/cross-tools as soon as they are available
without remembering a previous version of the same program in a
different location.
Setting the user file-creation mask (umask) to 022 ensures that newly created files and directories are only writable by their owner, but are readable and executable by anyone (assuming default modes are used by the open(2) system call, new files will end up with permission mode 644 and directories with mode 755).
The CLFS variable should be set to the
chosen mount point.
The LC_ALL variable controls the
localization of certain programs, making their messages follow the
conventions of a specified country. If the host system uses a version
of Glibc older than 2.2.4, having LC_ALL
set to something other than “POSIX” or “C” (during this chapter) may cause issues if you
exit the chroot environment and wish to return later. Setting
LC_ALL to “POSIX” or “C” (the two are equivalent) ensures that
everything will work as expected in the chroot environment.
By putting ${CLFS}/cross-tools/bin at
the beginning of the PATH, the
cross-compiler built in Constructing
Cross-Compile Tools will be picked up by the build process for
the temp-system packages before anything that may be installed on the
host. This, combined with turning off hashing, helps to ensure that
you will be using the cross-compile tools to build the temp-system in
/tools.
Finally, to have the environment fully prepared for building the temporary tools, source the just-created user profile:
To access the special environment launch the bash shell as follows:
export CLFS=/mnt/clfs; bash --rcfile ${CLFS}/.bashrc
To use this environment in a shell script do as follows:
export CLFS=/mnt/clfs ; source ${CLFS}/.bashrc
The following script will make it easier to open a shell with the desired environment:
cat > ${CLFS}/launch.sh << "EOF"
#!/bin/sh
bash --rcfile `dirname $0`/.bashrc
EOF
chmod +x ${CLFS}/launch.sh