The help chapter provides information on how you may access the documentation of the GNU/Linux system. There is normally a document describing every single tool you have installed, even if its
only brief...
man This command displays summary information on a program from an online manual. For example typing man man will bring up the manual page for man (the manual page viewer). Note: q is the
quit key.
Command syntax:
man program_name
Also try
Specifying the section of the manual page, sometimes the man page is different for the same tool in different sections, note sections are numbered 1 to 9. Use apropos to find which section number
to look in.
The syntax to look at a different section is:
man section_number tool_name
For example:
man 2 time
This will show you the man page called time in section 2, the equivalent page in section 1 is completely different
man -K
keyword Search the manual pages for a string, as in it will search all manual pages for a particular string within each individual man page, it will then prompt whether you would like to view each
page it will find. Use double quotes " and " if there are spaces in the string you are typing.
Speed issue
Please be warned that this method is going to be really, really slow. You are searching *all* man pages for a string
man -f
command This will list details associated with the command. The root user must run makewhatis (see below) before this command will work.
Equivalent to whatis
This command is the same as running whatis
info Provides a more detailed hyper-text manual on a particular command, this only works for some commands.
Command syntax:
info program_name
whatis Displays a one line description of what a program does. The string needs to be an exact match, otherwise whatis won't output anything. Relies on the whatis database (see
below).
Command syntax:
whatis program_name
makewhatis Make the whatis database for apropos, whatis and man -f.
Root Privileges
This takes some time and you require root privileges to do this.
apropos Searches the whatis database for strings, similar to whatis except it finds and prints anything matching the string (or any part of the string). Also relies on the whatis database
(see above).
Command syntax:
apropos string
Equivalent to...
apropos is the same as doing man -k (lowercase k).
Please note
You need to run makewhatis (as root) so whatis, man -f and apropos will work.
Also try
Using a program with the -?, --h, --help, and the -h options, they will display very short summary information on the command usage options.
