Linux Server Hacks, Volume Two

Hack #32. Give Your Tab Key a Workout

Use bash programmable completion to autocomplete much more than just filenames.

Tab completion in the bash shell isn't new, and I don't know how I'd live without it. Being able to type, for example, ls fo<tab><tab> and get a list of five or six files that start with "fo" can be very handy. Got a long script name you always mistype? Just type the first few letters and hit Tab twice, and bash will try to complete the name for you. This is a wonderful time-saver that I, for one, sorely miss when I log into other Unix machines where the default shell is csh and tab completion is not set up by default (causing control characters to appear on the command line instead of nice, clean, filenames).

In bash v2.04, "programmable" completion was introduced into the shell. This lets you add strange and wonderful bits of goodness to your bash initialization routines (usually found in ~/.bashrc and ~/.bash_profile).

Tip

Your bash initialization routines are dependent on how your shell environment is set up—bash can use a global /etc/bashrc, a ~/.bash_profile, a ~/.bashrc, a ~/.profile, and I believe a ~/.login file to get its initialization info.

Here's quick example:

	complete -f -X '!*.@(sxw|stw|sxg|sgl|doc|dot|rtf|txt|htm|html|odt|\
	ott|odm)' oowriter

This looks pretty cryptic, but really it's quite simple. complete is a bash built-in keyword that causes the shell to try to complete the text before the cursor on the command line. The -f flag means we'll be looking ...