SYS: Locate, read, and use system documentation including man, info, and files in /usr/share/doc.

To get information about a command (here ps), type:

# man ps

Sometimes several man pages exist for a command, to know them, type:

# whatis ps
ps (1) - report a snapshot of the current processes
ps (1p) - report process status

If you are not sure about the command name and want to search for a string (here ps), type:

# apropos ps
capsh (1) - capability shell wrapper
...
getpt (3) - open the pseudo-terminal master (PTM)

To update the whatis database, type:

# makewhatis

Alternatively, some commands (here ipc) have additional documentation that you can get by typing:

# info ipc

To get the list of these commands, type:

# ls /usr/share/info

Finally, most packages come with their own documentation in the /usr/share/doc directory.