echo $? displays ending value of last program run.

pwd Utility that shows your current working directory.

ldd Displays all files linked to an executable.

less useful unix pager

head In unix displays begining of file

tail In Unix displays end of file

grep In Unix displays parts of file with a specific pattern

Quoting Matt Haas“ Symbol Description * match 0 or more characters ? match exactly one character [ ] character class - match any of the enclosed characters. [^ ] inverted character class - do not match any of the enclosed characters.

”

** wc utility word count