The biggest problem with the UNIX manual set is finding what you want, given that you don't already know what you're looking for. For example: you want to search for a string in a file. If you don't remember that the command you want is called grep , how will you ever find it?
The apropos command, which is equivalent to man -k (and sometimes just an alias for man -k ) helps to solve this problem. It's not always successful, but it's better than nothing. It looks through headings of all the "man pages" and prints any that match a given keyword. For example, to figure out how to search for a string, try the command:
We've cut some of the output for convenience, but you can see what you want: to search for a string, you clearly want to use grep or one of its relatives.
All BSD and SVR4 systems support apropos . However, there are plenty of SVR3 (and earlier) systems kicking around that don't. If you're facing this problem, see article 50.3 .
MILD FLAME: Over the years, the output from apropos has gotten quite cluttered. It's considerably less useful now than it was ten years ago.