If you know what you want to do, but you do not know which command to use, use the apropos command to locate commands by keyword lookup. The apropos command lists all commands that have one-line summaries that contain any keywords you supply. The output of the apropos can be lengthy, as some keywords might appear in many places.
The apropos command is only available if your system administrator has set up a special database of command descriptions.
To view examples of apropos output, type one or more of the following commands.