A new dedicated server can be somewhat daunting, especially if you are new to Unix and Linux system administration. Assuming you have an unmanaged server, there will be times when you need to access your server via SSH and access the operating system’s command line. If you understand the command protocol for one version of Unix, you should be relatively proficient in others, such as Linux, FreeBSD, and Solaris.
When you need help with a Linux command, the easiest way to find out information is to append “–help” or “-h” to the end of it.
$ ls –help
This help will show you usage (usually the command followed by options and acceptable information), and it will then list other flags that you can append to commands, followed by their meanings.
When the help flag is not enough, you can look at the full manual using “man”.
$ man ls
A manual page will provide the same information as “–help” with more depth and often examples of usage.
If you just need a brief description of what a command is, you can use “whatis”.
$ whatis ls
Output: ls (1) – list directory contents
If you know what the command is but need to know where it is, you can type:
$ whereis ls
$ which ls
Finally, if all else fails and you still cannot figure out something, you can read the developer’s documentation. For larger applications, this will usually be more extensive than a simple man page and may even have tutorials.