GETTING HELP IN LINUX
Read man page of the command
This is the easy and most effective method to get quick help on any Unix command. I’ve seen a lot of people (especially newbies) getting bored reading the man pages.
While Unix/Linux man pages might not have a lot of practical examples, it does explain all the options available for a command in a detailed manner.The man command shows detailed manuals for each command. These are referred to as “man pages.” For example, if you wanted to view the man page for the wget command, you’d type man wget.
Man pages generally contain much more detailed information than you’ll get with the -h or –help options
-h or –help
If you’re not sure how to use a specific command, run the command with the -h or –help switches. You’ll see usage information and a list of options you can use with the command. For example, if you want to know how to use the wget command, type wget –help or wget -h.
This will often print a lot of information to the terminal, which can be inconvenient to scroll through. To read the output more easily, you can pipe it through the less command, which allows you to scroll through it with the arrow keys on your keyboard. For example, use the following command to pipe wget’s help output through less:
wget –help | less
Some programs don’t have man pages – or have an incomplete man pages – and store their documentation as info documents.
The apropos command searches for man pages that contain a phrase, so it’s a quick way of finding a command that can do something. It’s the same thing as running the man -k command
The whatis command shows a one-line summary of a command, taken from its man page. It’s a quick way of seeing what a command actually does.
[root@localhost ~]# whatis man man (1) - an interface to the on-line reference manuals man (1p) - display system documentation man (7) - macros to format man pages