Absolutely Important UNIX Commands

Absolutely Important UNIX Commands

cat f List contents of file

cat f1 f2 >f3 Concatenates f1(file 1) & f2(file 2) into f3(file 3)

cd returns you to your home or main directory

cd / takes you to the root, as far up (to the left) as far as possible

cd to move down (right in the pathname) a directory

cd .. moves you up (left in pathname) a directory; likewise,

cd ../../.. :- moves you up (left in the pathname) 3 directory levels

chmod ### :- changes your protections. The order is: you|group|universe (rwxrwxrwx).
There will be either a d or - before it. If there's a d, then it's a directory. If there's not, then it's a file.
You set the protections in the order rwx (read=1, write=2, execute=4). So, to set the protections for the
directory directoryname: you rwx, group r-x, universe r--, you would enter:chmod 751 .

clear :- to clear screen

compress :-compresses the file filename and puts a .Z extension on it. To uncompress it, type uncompress

cp f1 f2 :- Copy file f1 into f2

cp -r D1D2 :- copies the directory D1 and renames it D2

^-c (ctrl-c):- to kill a running process


^-d (ctrl-d):- to close an open window

df :- gives disk usage

diff f1 f2 :- Lists file differences

dig host :- domain name, IP address, and alias information for the given host.

dosdir :- to do a "dir" (~ls in UNIX) on a DOS floppy in the disk drive
dosread to read a file from a DOS floppy to your computer account
doswrite to write a file from your computer account to a DOS floppy

du :- lists all subdirectories and their sizes (in blocks?) and total directory size (in blocks?) (takes a long time)

du -a :- lists all files and their sizes (in blocks?) in present directory and total directory size (in blocks?) (takes a long time)

du -s:- lists overall directory size (in blocks?) (long but clean)

env :- shows current environment set-up

find :- Searches the named directory and it"s sub-directories for files. Most frequently called like this:
find ./ -name "t*" -print
Which searches the current directory ( and all of its sub-directories ) for any files that begin with the letter "t" and then prints them out. If you are looking for a specific filename, then replace "t*" with "filename", and "find" will print out all incidences of this file.

finger @.:- (e.g., finger johndoe@ksu.edu fingers Johndoe at Kent State University)

ftp :- establishes an ftp link with machinename

gzip :- produces files with a .gz extension.

gunzip :- decompress files created by gzip, compress or pack.
ispell f Interactively checks the spelling of the file f, giving logical alternatives to the misspelled words. Type "?" to get help. "ispell" can be accessed from the command line, and also through emacs with M-x ispell-buffer.

kill -9 -1 :- (from a remotely logged-in site) kills all running processes (essentially forces a logout) *not to be used unless nothing else works* kill -9 process-id# - kills a running process

lpq :- shows UNIX print queue

lpr :- to print the file

lpqrm job# :- removes job from printer queue

ls :- shows listing of files in present directory

ls -a :- shows listing of all files in present directory

ls -l :- shows long listing of files in present directory

ls -la | more :-shows long listing of all files in present directory

man command :- shows help on a specific command.

mkdir :- D creates a new directory called D

more :- to view the contents of a file without making changes to it one screen at a time. Hit q to quit more.

mv f1 f2 :- Rename file f1 as f2

mv f1D :- moves the file called f1 to the directory D

nslookup host:- domain name, IP address, and alias information for the given host. e.g.,nslookup www.kent.edu gives related data for www.kent.edu

passwd:- to change your password (takes an hour or so to take effect on all machines)

ping host :- to test if the host is up and running.

pwd :- present working directory

ps :- Shows processes running

ps -flu :- Shows detailed description of processes running

pquota:- Shows printer quota

quota -v :- Shows current disk usage and limits.

rlogin :- allows you to remotely log in to another machine on which you have access privileges

rm f :- Delete (removes) the file f.

rm -i f :- To be prompted for confirmation before you remove a file f, at the UNIX prompt, type

rm dir D :- Delete (removes) the empty directory D

rm - r D :- removes the directory named D and its contents - use with caution

s f :- Alphabetically sort f.

talk :- establishes an e-tak session with user@machinename

tar :- combines multiple files into one or vice-versa

telnet :- allows you to remotely log in to another machine on which you have access privileges

uncompress :- uncompresses filename.

users :- shows who's logged in on the machine

vi :- to open the file called filename in the vi text editor

who :- Shows who is currently logged on the system.

whoami :-shows username of person logged in that window

whois domain_name :- lists the domain registration record, e.g., whois kent.edu will produce the domain record for kent.edu

* :- wild card character representing any # or characters

date :- shows the time and date

date -u :- shows greenwich mean time

. :- a short cut that stands for the location you are at in a pathway. ex. cp (file (though a pathway) (. (the location you are at)

.. :- move to parent directory from any comand ex. mv (file name) ..

pwd :- shows where you are in the pathway

? :- wild card character representing one character, can be used in succesion

~ :- abbreviation for the home file ex. ls ~ lists files in home dir w/o moving there

zip :- best compression for IBM files.