More koooolest ones.....

File system navigation / directories
* pwd [options] - to obtain/print the name of your current/working directory.
* cd [options] [directoryname | ~ | ./ | ../ | - ] - to change your working directory.
* ls [options] directoryname - to list the contents of directories.
* mkdir [options] directoryname - to create new directories.
* rmdir [options] directoryname - to remove/delete directories.
* cp [options] source destination - to copy files and directories.
* mv [options] source destination - to move files and directories.
* rm [options] filenamelist - to remove/delete files.
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Exiting from a shell prompt (to close a terminal window or to log out)
* exit
* or by pressing - the general end of text control character.

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Searching for files by name
* locate [options]
* find [options]
* slocate [options]

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Viewing text files

* cat [options] filename - to display the file contents without pause or break.
* less [options] filename - to display file contents page by page.
* more [options] filename - to display file contents page by page.
* tail [options] filename - to display the last few lines of a file.
* head [options] filename - to display the first few lines of a file.

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traceroute

Traces the existing network routing for a remote or local server
Most common use: traceroute hostname
(replace hostname with the name of your server such as harquch.com)
This is a very powerful network command that basically gives the exact route between your machine and a server. In some cases you can actually watch the network hops from country to country across an ocean, through data centers, etc.
This comes in handy when trying to fix a network problem, such as when someone on the network can not get access to your server while others can. This can help identify the break or error along the network line. One strong note to you is not to misuse this command! When you run the traceroute everyone of those systems you see listed also sees YOU doing the traceroute and therefore as a matter of etiquette and respect this command should be used when necessary not for entertainment purposes. A key characteristic of gainfully employed server administrators: knowing when to use commands and when not to use them!