Basic commands for UNIX that ought to be known:

Directories, information:
-------------------------

ls                              LiSt.  Shows contents of current directory.
cd                              Change Directory
mv                              MoVe.  Moves a file (leaves no copy). 
cp                              CoPy.  Like mv, but leaves a copy.
mkdir                           MaKe DIRectory
rm                              ReMove.  Delete, cannot be undeleted.
rmdir                           ReMove Directory
pwd                             Print Working Directory
chmod                           Change permissions.
du                              Disk Use.  Shows totals in kilobytes.

System Information:
-------------------

w                               Who.  Lists users, login times, and status.
who                             Lists users, and login sites.
finger                          Shows personal information.
date                            Shows current date and time.
uptime                          Shows system status, and load averages.
man                             MANual pages.  Complete online reference.
ps                              ProceSses.  Show what programs are being run.
top				Shows top users of CPU and RAM

Task Management:
----------------

^C                              Standard interrupt
^D                              End of Text (EOT)
^Z                              Stop current program
fg                              ForeGround (resume) a program
bg                              BackGround (resume at low priority) a program
kill                            Terminate a stopped program
jobs                            List all running or stopped programs.
&                               Run in background (append at program start).

File Manipulation:
------------------

more                            View a file, one screen at a time
less                            View a file.  Like more, but better
cat                             CATenate.  Copy a given input to a given output
grep                            Get Regular Expression and Print. Search files.
head                            Show the first lines of a file
tail                            Show the last lines of a file
touch                           Update last change on file
vi                              Visual editor.  Standard for UNIX.

Plumbing:
---------

>                               Redirect output to a file
>>                              Append output to a file
2>                              Redirect errors to a file (sh and bash)
<                               Send file as input
|                               Send output of one program to input of next

Communications:
---------------

telnet                          Connect to another computer
ftp                             File Transfer Protocol
^S                              Hold Screen
^Q                              Release Screen
stty                            Change terminal settings
write                           Send text to another user's screen
talk                            Enter split-screen chat mode with another user

Other:
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yes                             Repeats 'yes' infinitely
biff                            Lets you know when new mail has arrived
clear                           Clears the screen
script                          Make a log of what appears on the screen
nohup				Let a process run after logging out
lpr				Print
lpq				Check print queue
rlogin				Remote login
tar				Tape ARchive.  Used to consolodate files.
gzip				Compress/Decompress files (.gz extension)
gcc				C compiler