What is a Command

UNIX commands consist of three components:

yppasswd

changes user password

date

tells the date and time

who

lists other logged in users

tell what other users are doing

logout or exit

ends a unix session

ends a unix session

man <commandname>

shows information on commandname, includes options and arguments

finger <username>

shows more complete information on username

talk <username>

allows you to hold an interactive conversation with username. To exit the talk command type: <ctrl> C

rusers

gives a list of who's logged in on a local machine, option -l gives the users real name too

- options are typically single letters preceded by a hyphen
- several options can be used at the same time with restriction made by the command

Example 1:

	ls -F 


Results 1:

	junk     
	termpaper
	stuff/   
	programs/

- arguments are typically strings or filenames or Path names

Example 2: (Here: you do not know whick are directories or executables or text files

	ls ~/programs


Results 2:

	a.out
	test.c
	steve.doc
	cs115