Linux From Scratch: Version 5.0-pre2
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# Setting up the environment

While logged in as user lfs, issue the following commands to set up a good work environment:

    cat > ~/.bash_profile << "EOF"
    set +h
    umask 022
    LFS=/mnt/lfs
    LC_ALL=POSIX
    PATH=/tools/bin:$PATH
    export LFS LC_ALL PATH
    unset CC CXX CPP LD_LIBRARY_PATH LD_PRELOAD
    EOF

    source ~/.bash_profile

The `set +h` command turns off `bash`'s hash function. Normally hashing is a useful feature: `bash` uses a hash table to remember the full pathnames of executable files to avoid searching the PATH time and time again to find the same executable. However, we'd like the new tools to be used as soon as they are installed. By switching off the hash function, our "interactive" commands (`make`, `patch`, `sed`, `cp` and so forth) will always use the newest available version during the build process.

Setting the user file-creation mask to 022 ensures that newly created files and directories are only writable for their owner, but readable and executable for anyone.

The LFS variable should of course be set to the mount point you chose.

The LC_ALL variable controls the localization of certain programs, making their messages follow the conventions of a specified country. If your 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 trouble if you exit the chroot environment and wish to return later. By setting LC_ALL to "POSIX" (or "C", the two are equivalent) we ensure that everything will work as expected in the chroot environment.

We prepend `/tools/bin` to the standard PATH so that, as we move along through this chapter, the tools we build will get used during the rest of the building process.

The CC, CXX, CPP, LD_LIBRARY_PATH and LD_PRELOAD environment variables all have the potential to cause havoc with our Chapter 5 toolchain. We therefore unset them to prevent any chance of this happening.

Now, after sourcing the just-created profile, we're all set to begin building the temporary tools that will support us in later chapters.

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