This page contains brief descriptions and examples of a handful of commands that can be executed in the LINUX environment.  It is by no means the intent of this page to contain a complete list of all useful LINUX commands, but to give its audience a gentle guide to a few useful ones. 

Suggestions on commands to add are welcomed and will be added as time permits.

man - manual

man is the system's manual pager, which provides an interface to the on-line reference manual. 

Here are a few examples of how to use the man paes:

man <topic>: read the manual page for <topic>. <topic> in this example is ssh

$ man ssh

man -s  <section_no> <topic>: the -s option allows usr to specify the section number of the section to search for the manual page info for <topic>

$ man -s 2 open

man -k <topic>: -k option allows usr to search the short descriptions and manual page names for <topic>

>> man -k print

apropos - search for help

same as man -k.

less - view output by page

less is a file reading filter for console viewing. less, like many other LINUX utilities, take several optional parameters.  Type man -s 1 less at the console for more information on its proper usage. less allows you to move forward and backward in a file.  To search for an expression when view the output of less, enter the / character.

Here are a few examples of how to use less:

man <file>: view <file> page by page

$ less myfile.txt

<exp> | less: pipe the output of <exp> to less

$ ls -al | less

grep - search and print lines matching a pattern

grep prints out the lines of some input that contains a matching regexp.A regexp is a general regular expression -- details are provided in the man pages.

Here are a few examples of how to use grep:

grep <regexp> <file>: search for <regexp> in <file>

$ grep foo myfile.txt

<exp> | grep <regexp>: search for <regexp> in the output of <expr>.

$ ls -al | grep txt

grep <option> <regexp> <file>: grep takes a number of options and file can be a winldcard

$ grep -r -al | grep txt


sh(1), csh(1), tcsh(1), fork(2), pipe(2), wait(2)


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