File: unix.html
Updated September 24, 2008

Basic Unix Commands
Unix is an operating system used in our work stations. Its advantages are:

• It can run on different types of computers
• It is multiuser and multitasking operating system.

Some of the current versions of UNIX are:

• HP - UX
• Linux ( PC based free)
• Sun OS

User Interfaces

Users interact with UNIX in two distinct ways:

• Command line interface
• Graphical user interface ( GUI) such as: X Windows ( MIT), X-Win32, and others

FILES - DIRECTORIES - SHELLS

Files

Files are the most basic units of information that can be stored. Files may contain text, programs, data, images, sounds, or other items.

Directories

If files are like the documents in a filing cabinet, then directories are like drawers of a filing cabinet ( or folders of Windows XP). Hierarchical directories or trees may be constructed. A directory that is contained in another directory is often called a subdirectory. The very top directory in the hierarchy is called the root directory and it is denoted by the / character.

/home/jyk0/private/engr1

will be the name of my private engineering 1 directory.

/home/jyk0/public/engr1

will be the name of my public engineering 1 directory.

Shells

The shell program accepts commands from the user, interprets them and executes them thus providing an interface with the computer. An early UNIX shell is the C shell ( or csh).Was popular for interactive use. Lists of commands that will be executed by the shell are called shell scripts. In recent years there are other modern shells such as Korn shell (ksh) , Tenex C shell ( tcsh), Bourne shell ( bsh), etc.

Commands Summary

Name	Purpose	Syntax	Notes
&	places a process in the background	command &
cat (or more )	displays the contents of a file	cat filename
cc ( or gcc )	compiles C programs and creates an executable file ( default name a.out)	cc FileName.c [options]	-o name of executable and many other options
c++ ( or g++)	compiles C++ programs and creates an executable file ( default name a.out)	c++ FileName.cpp [options]	-o name of executable and many other options
cd	changes directory	cd directory_name	.. indicates parent directory example: cd ..
clear	clears the screen	clear
cp	copies files	cp source destination	. indicates current directory
emacs	invokes the editor	emacs [filename]	emacs & will keep xterm active
f77	compile FORTRAN 77 programs and creates an executable file ( default name a.out)	f77 fileName.f [options]	-o name of executable and many other options
ifort	compile FORTRAN 90 programs and creates an executable file ( default name a.out)	ifort fileName.f 90 [options]	First run the command ( or include in profile) . /usr/local/bin/setup-intel-compilers (note the leading dot and space)
Our LEAF specific:	$g++ will compile C++ $F90 will compile f 90	But you must first run both statements on the right ( or include in profile)	. /usr/local/vni/imsl/cnl600/linux/bin/cnlsetup.sh . /usr/local/vni/imsl/fnl600/lnxin100i32/bin/fnlsetup.sh (note the leading dot and space).
exit	logs a user out	exit
jobs	list the running processes	jobs
kill	stops a process	kill [ option] process number	-9 immediate kill
ls	displays the contents of current (or specified) directory	ls [option] dirname	-l long list -a all files
man	the unix help system	man command	try man g++ , man more , etc
mkdir	makes a new directory	mkdir directory_name
more ( or cat)	displays the contents of a file one screen at a time	more filename
pwd	prints present working directory	pwd
rm	removes a file	rm filename
rmdir	removes a directory	rmdir directory_name