Here's a breakdown of the man -k PostScript command line:

man.
The command name, tells the computer to look at the manual pages.
These provide documentation for commands. For example, man whoami
will give you documentation on the whoami command.

-k.
The option, changes the behavior of man. Normally man expects a
command name, such as whoami, for an argument and looks for
documentation of that command. But with the -k or -apropos option,
it expects the argument to be a keyword. It then gives a list of
all manual pages with that keyword in their description.

PostScript.
is the argument; because we used the -k option, it's the keyword
to search for.

-k and PostScript are both parameters.

Go ahead and type man -k PostScript, and you will see a list of all the
manual pages on your system that have something to do with PostScript. If
you haven't installed much software, you might see the message
PostScript: nothing appropriate instead.

Describing the Command Line

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