Unix Command List

Unix is a popular operating system for workstations and minicomputers. Unix is the Operating System on the pwa.sandiego.edu server (basically all the main computers here on campus). It is a text based system meaning that there are no graphical interfaces to help you execute tasks. It also means you have to type in text commands to make things happen. IT ALSO MEANS THAT YOU MUST TYPE IN THE COMMAND EXACTLY CORRECT OTHERWISE IT WILL NOT EXECUTE THAT COMMAND. These pages are meant to help you with when you need to work on a Unix system, not all Unix commands are presented, only the most frequently used commands.


Math Commands

factor             - finds the factors of an integer

                         factor 324

dc                   - desk calculator

                        first type in dc  then hit enter, now enter in digits and what you want to do

                        3 4 * p q

                        3 4 5 6 * p q

                        5 5 6 + p q


            other dc commands [also refer to picture below]

                        use _ for negative numbers (Unix will confuse ‘-‘ as subtraction)

                        ^ use for exponential values

                        v for square root

                        the ‘p’ [postfix notation] tells the computer to calculate (like enter button)

                        the ‘q’ tells the computer to quit the desk calculator function.




Date and Calendar Functions

date    - shows the date and time

cal       - show calendar

            this particular function can be handy in finding out dates from many, many years back      (all the way to year 0 AD), can print entire year or month year cal 1999    cal 9 1752



Communication Commands

finger -          provides information on users; idle time, last logged in, real name, etc

                        finger [username]  finger crebman

who    -           find out who is currently logged onto the system

talk     -           communicate on-line with a split screen

write   -           communicate on-line without a split screen

mesg  -           deny or permit the write function



pine    -           email

mail    -           mail function without the GUI interface of PINE, complicated and not

                        recommended to use mail carlr

trn       -           sets up a news group in pine (takes about 10 minutes), for viewing news



Text Commands

diff      -           compare two files

                        diff filename1 filename2

nl         -           count the lines in a file and display them

                        nl filename

wc       -           count words, lines, chars in file

                        wc filename

cat      -           show contents of ASCII file

                        cat filename | pg ßcauses pagination through pipe

head   -           shows the first part of ASCII file

tail       -           shows the last part of ASCII file

more  -           shows the file in increments

                        more filename

spell   -           find spelling errors in a file (prints out unrecognized words)

                        spell filename

grep   -           finds a pattern (word) in a file and prints outs the entire line

                        grep word filename

pico    -           a text editor within Unix that allows you to make changes to a file and save

                        pico filename

vi         -           another editor within Unix that is more complicated but allows more functions

System Commands

logout            -           allows user to get out of Unix, end session

exit     -           also allows user to get of Unix, end session

login   -           allows user to log into another account without logging out

telnet  -           allows user to telnet into another computer system without ending session

                        telnet pwa.sandiego.edu

whoami         find out which account you are using         

passwd         allows you to change your password, type your old password, then new

                        password twice

du       -           shows your disk usage in blocks

man    -           this is the online Unix manual access command, having trouble getting

                        a command to work, just type man and the command, also works for

                        subjects too

                        man dc

                        man mail

mkdir -           create a new directory (folder)

                        mkdir directory_name

rmdir  -           remove a directory (the directory/folder must be empty first)

                        rmdir directory_name

cd       -           changes to a new directory, note the space after the cd

                        cd new_directory_name

cd ..    -           changes to the parent directory (folder) that is immediately above your

                        current directory

                        cd . .   [note the dots is the directory name in this case]

pwd    -           present working directory


clear -             clear screen

System Commands Continued

cp -                 copy file

                        cp filename1 newfilename

mv      -           move file (copy and delete the original)

                        mv filename 1 newfilename

ls         -           directory listing, can list entire directory, or list all certain file types

                        ls         ls *.exe (the second lists all .exe files)

ls -al;  -           list all files

ls -l      -           show attributes of files

rm       -           remove file

                         rm filename


Special System Command the chmod command

This command is very important and very dangerous. It controls who has access to your files and what they can do to them. Unix designates three different types of access designations, user, group, and others. User refers to your own personal access, others refers to any user who can hit the sunset system, in this case the entire world, group is somewhere in between, in this case, any person with a sunset account. There are three types of access authorization, read (r), write (w), and execute (x).

            Read basically just allows a person to see your file but not do anything, for example all of your web pages need to be read allowed for viewing.

            Write refers to a person’s ability to write changes to your files and generally you would not allow public write access, otherwise your web page could say something you might not want it to.

            Execute is the ability to run a program file on your account, in this example there will be times when you’ll designate the public access to execute, and other times you will not, it just depends.  The command looks like this:


chmod           change attributes or permissions on files

                        chmod ugo+w filename


Notice the order of ugo ~ refers to the three groups, user, group, other, look at the example below;first column D means dir, next 3 spaces =u, then next 3 refer to g, last 3 spaces = o



With chmod you can add read, write, execute all at the same time, or only one, or a combination. You can also delete access either one, all , or a combination. Essentially the command reads as such


chmod [ugo][add(+) or delete(-) permission] [specify what type of access granted or denied]


other examples (what is happening in each case?)


chmod ugo-x filename    _____________________________

chmod o+r filename        _____________________________

chmod g+rw filename   ______________________________

chmod uo-rwx filename ______________________________****


*** what is the danger of this last example?? *****



^C       Control C will quit whatever process/command/task you have started

<>        These keys redirect input and output, to the left is the input file, and to the right is the output. count.exe > total  [input is count.exe program, output is total

|           This key is called a pipeline. It basically separates commands and lets you execute multiple commands. A common example is who| pg, which basically tells you who is on, but only shows one page at a time.


set      -           shows settings

                        to change enter set prompt=$


alias   -           creates new command

                        alias dir ls –al [this command will execute the ls –al when you type dir]

                        alias                [this typed in alone will show all alias definitions]

unalias -        removes alias definitions

                        unalias dir


at         -           this specifies a time to run a batch process

                        at 04:27

                                    calendar 9 1752 | mail carl@career.olemiss.edu

                        ^D [terminates]

                        this command will send a one month calendar to carl at 4:27 am

at -l     -           show at processes

at -r     -           remove at processes

ps       -           show status of processes

kill       -           stop processes (must specify a process)

                        kill 2112

.files -             indicate hidden files

.project          limited to one text line

.plan               this can have multiple lines and can list whatever you want

history           to see the previous commands that you have typed in, can run commands, ex !-2

vacation        this will send an automatic reply to a sender, which can be useful  if you will be away for a while and will not be able to read your mail