Every Unix command has an associated ``man page,'' i.e. a terse description of the command usage and function. For example, man man will tell you more about how to read man pages. Unfortunately, if you don't know the name of the command you're looking for, this doesn't help you very much. In that case, try man -k keyword, which will search for man pages with keyword in the description. This often leads to a bewildering screenful of possible commands. Generally you need only concern yourself with man pages from section 1 (Unix commands), 2 (library calls), and 3 (C and FORTRAN functions), which are indicated by the corresponding number in parantheses in a man -k listing (sometimes with a small letter appended, e.g. 3c for C functions). WARNING: the man command often behaves differently on different operating systems. For example, under SunOS, by default only the first matching man page is shown (use -a to show them all) and sections are specified using -s.