mknod -m 0666 /dev/null c 1 3: Glibc needs a null device to compile properly. All other devices will be created in the next section. touch /etc/ld.so.conf One of the final steps of the Glibc installation is running ldconfig to update the dynamic loader cache. If this file doesn't exist, the installation will abort with an error that it can't read the file, so we simply create an empty file (the empty file will have Glibc default to using /lib and /usr/lib which is fine). sed 's%\$(PERL)%/usr/bin/perl%' malloc/Makefile.backup > malloc/Makefile: This sed command searches through malloc/Makefile.backup and converts all occurrences of $(PERL) to /usr/bin/perl. The output is then written to the original malloc/Makefile.in which is used during configuration. This is done because Glibc can't autodetect perl since it hasn't been installed yet. sed 's/root/0' login/Makefile.backup > login/Makefile: This sed command replaces all occurences of root in login/Makefile.backup with 0. This is because we don't have glibc on the LFS system yet, so usernames can't be resolved to their user id's. Therefore, we replace the username root with user id 0. --enable-add-ons: This enables the add-on that we install with Glibc: linuxthreads --libexecdir=/usr/bin: This will cause the pt_chown program to be installed in the /usr/bin directory. sed 's/cross-compiling = yes/cross-compiling = no/' config.make.backup > config.make: This time, sed searches through config.make.backup and replaces all occurences of cross-compiling = yes with cross-compiling = no. We do this because we are only building for our own system. Cross-compiling is used, for instance, to build a package for an Apple Power PC on an Intel system. The reason Glibc thinks we're cross-compiling is that it can't compile a test program to determine this, so it automatically defaults to a cross-compiler. Compiling the test program failes because Glibc hasn't been installed yet. exec /bin/bash:This command will start a new bash shell which will replace the current shell. This is done to get rid of the "I have no name!" message in the command prompt, which was caused by bash's inability to resolve a userid to a username (which in turn was caused by the missing Glibc installation).