clear		- clear console.
cd		- change directory.
ls		- list directory contents.
mv		- move a file (also used to rename a file).
cat		- conCATonate text file to STDOUT.
more|pg		- conCATonate text file in console sized chunks.
head		- concatonate head (beginning) of text file to STDOUT.
tail		- concatonate tail (end) of text file to STDOUT.
id		- reports information about the user who invokes it.
finger		- reports information about users (.plan and .project)
who		- reports information about users logged in
	-u	- time since last activity
	-T	- Reports messages (+) to user's terminal or not (-)
	-q	- Login IDs and a count of the logged-in users
	-i	- "Who am I?" reports information on self
su userid	- "Switch User" (will default to root if no userid argument)
du		- reports information about disk usage (MB,KB,etc).
ps		- reports active processes.
dircmp		- examines the contents of two directories+subs
bc		- Basic Calculator
dc		- Desktop Calculator (uses RPN or Reverse Polish Notation)
crypt ["key"]  encryptfile

from - list senders of mail
write - write to another logged-in user
as - assembler, specific to each machine architecture
time - time a command
crontab - maintain periodic tasks
ld - the UNIX loader
lint - check C source code
nice - run a command at low priority
nohup - run a command immune to hangups
apropos - locate commands by keyword lookup
whatis - describe what a command is
whereis - locate source, binary, or man page for a program
cmp - compare two files
diff - compare the contents of two ASCII files
file - determine file type
uniq - report (or delete) repeated lines in a file
wc - count lines, words, and characters in a file
fold - fold long lines to fit output device
script - make typescript of terminal session
^y - suspend process at next input request
^z - suspend current process
manpath - show search path for man pages
printenv - print out environment
diction - identify wordy sentences
diffmk - mark differences between files
explain - explain phrases found by diction program
hyphen - find hyphenated words
ispell - check spelling interactively
ndx - create a subject-page index for a document
spell - find spelling errors
style - analyze surface characteristics of a document

#----------------------------------------------------------------------------
cal - Print Calendar to STDOUT
	% cal 1999	- 12 Month Calendar
	% cal 9 1752	- Calendar for September 1752 (take a look at missing days)

#----------------------------------------------------------------------------
<	redirect input
>	redirect output
0>	redirect input
1>	redirect output
2>	redirect error output
3>	redirect ~ (if you how file is used)