The presence / absence of the which program in the main LFS book is probably one of the most contentious issues we have on the mailing lists. It has resulted in at least one flame war in the recent past. To hopefully put an end to this once and for all, we here present the various options for equipping your system with "which". The first option is simply to use a bash alias: alias which='type -p' This command can be put in your ~/.bash_profile or ~/.bashrc file in order to be set up each time you log in (see man bash for more information on the bash login files). This will not always work however, for example it will fail when a program needs to use "which" but doesn't spawn a shell. The second option is to create a simple script: cat > /usr/bin/which << "EOF" #!/bin/bash type -p "$@" EOF chmod 755 /usr/bin/which chown root:root /usr/bin/which This should generally work OK and is probably the easiest solution for boxes which don't need a good user environment to work in. The third option is to install the actual program which. &which-intro; &which-inst; &which-desc;