Basic UNIX commands

Here is a list of some common UNIX commands. This should get you started.

Command	What for	Advanced version	What does it do?
`man`	manual for UNIX commands	`man man`	First command to learn, manual on manual
`ls`	list contents of directory	`ls -latr`	list all files with more information, sort in reverse order than when it was created
`cd`	change directory	`cd -`	change to the last directory you were in
`cp`	copy files/directories	`cp -a`	copy while preserving all properties
`mv`	move file (change name)	`mv -i`	move but ask if you are overwriting an existing file
`rm`	remove (delete)	`rm -rf *`	delete everything, without asking and without mercy (very dangerous)
`less`	view an ASCII file	`less -S a.txt`	View `a.txt` without wrapping long lines

Command	What for	Example	What does it do?
chmod	Change access permissions in UNIX	`chmod 755 a.txt`	Allows everyone to read and execute the file `a.txt`
diff	compare two files and list differences	`diff a b`	COmpare the two files `a` and `b` and list differences
grep	print lines that match a pattern	`grep -i err a.log`	Print all the lines in the file `a.log` that contain `err` written big or small.
ps	List UNIX processes running	`ps -auxw`	List all processes for all users
sort	Sort text files line by line	`sort -nr a.txt`	Sort lines of `a.txt` in reverse numerical order

Tool	What is it used for
awk	modify files based on patterns
find	look for files that match a criteria
sed	replaces strings in text file
vi	Standard UNIX text editor