Home > Miscellaneous > Some Basic Unix Command Codes

Some Basic Unix Command Codes

$ ls          (list)
$ mkdir    (make a new directory or folder)
$ pwd      (present working directory)
$ cd         (change directory)
$cp          (copy)
$ mv        (move)
$ rm         (remove)
$ cat        (view entire file on screen)
$ more     (view by page)
$ diff        (differences)

$ compress *.txt       (compress all files with extension txt)
$ uncompress *.txt   (decompress all files with extension txt)
$ gzip *.txt                (compress all files with extension txt)
$ gunzip *.txt            (decompress all files with extension txt)
$ ulimit -a    (show how much space or other resources allocated to the user)

$ cd  /ftp/MAH_CW/manpeng
$ cd ~/temp        (where ~ means the home directory)

$ ls -ls                  (this lists more details of the files)

There are some important shortcuts in UNIX for specifying directories
. means “the current directory”
.. means “the parent directory,” i.e., the directory above the current directory, so cd .. will move you up one level.
~ means your home directory, so cd ~ will move you back to your home level


Custom commands available in the CS Lab but not on Linux systems elsewhere
have descriptions marked by an *asterisk.
Notice that for some standard Unix/Linux commands, friendlier versions
have been implemented; in the CS lab the names of such custom commands
end with a period.
TAB                         Command completion !!! USEFUL !!!
UPARROW                     Command history !!! USEFUL !!!

CTRL-C                      Interrupt current process.
CTRL-D                      If a program/command waits for input, end input.
*                           Replaces any string of characters in a file name
except the initial dot.
?                           Replaces any single character in a file name
except the initial dot.
~                           The home directory of the current user.
~abcde123                   The home directory of the user abcde123.
..                          The parent directory.
.                           The present directory.
/                           The root directory

ls ~/csc219/*.txt

COMMAND < FILE              COMMAND will take input from FILE.
COMMAND > FILE              Put output of COMMAND to FILE
COMMAND >> FILE             Append the output of COMMAND to FILE
COMMAND 2> FILE             Put error messages of COMMAND to FILE.
COMMAND 2>> FILE            Append error messages of COMMAND to FILE.
COMMAND > FILE1 2> FILE2    Put output and error messages in separate files.
COMMAND >& FILE             Put output and error messages in the same FILE.
COMMAND >>& FILE            Append output and error messages of COMMAND to FILE.

COMMAND1 | COMMAND2         Output of COMMAND1 becomes input for COMMAND2.
COMMAND | more              See the output of COMMAND page by page.
COMMAND | sort | more       See the output lines of COMMAND sorted and page by page.

h                           *Custom help.
COMMAND –help | more       Basic help on a Unix COMMAND (for most commands).
COMMAND -h | more           Basic help on a Unix COMMAND (for some commands).
whatis COMMAND              One-line information on COMMAND.
man COMMAND                 Display the UNIX manual page on COMMAND.
info COMMAND                Info help on COMMAND.
xman                        Browser for Unix manual pages (under X-windows).
apropos KEYWORD | more      Find man pages relevant to COMMAND.
help COMMAND                Help on a bash built-in COMMAND.
perldoc                     Perl documentation.

ls                          List contents of current directory.
ls -l                       List contents of current directory in a long form.
ls -a                       Same as ls but .* files are displayed as well.
ls -al                      Combination of ls -a and ls -l
ls DIRECTORY                List contents of DIRECTORY (specified by a path).
ls SUBDIRECTORY             List contents of SUBDIRECTORY.
ls FILE(S)                  Check whether FILE exists (or what FILES exist).

pwd                         Display absolute path to present working directory.

mkdir DIRECTORY             Create DIRECTORY (i.e. a folder)

cd                          Change to your home directory.
cd ..                       Change to the parent directory.
cd SUBDIRECTORY             Change to SUBDIRECTORY.
cd DIRECTORY                Change to DIRECTORY (specified by a path).
cd. ARGUMENTS               *Same as cd followed by ls

cp FILE NEWFILE             Copy FILE to NEWFILE.
cp -r DIR NEWDIR            Copy DIR and all its contents to NEWDIR.
cp. ARGUMENTS               *Same as cp -r but preserving file attributes.

mv FILE NAME                Rename FILE to new NAME.
mv DIR NAME                 Rename directory DIR to new NAME.
mv FILE DIR                 Move FILE into existing directory DIR.
ln -s FILE LINK             Create symbolic LINK (i.e. shortcut) to existing FILE.

quota                       Displays your disk quota.
quota.                      *Displays your disk quota and current disk usage.

rm FILE(S)                  Remove FILE(S).
rmdir DIRECTORY             Remove empty DIRECTORY.
rm -r DIRECTORY             Remove DIRECTORY and its entire contents.
rm -rf DIRECTORY            Same as rm -r but without asking for confirmations.
clean                       *Remove non-essential files, interactively
clean -f                    *Remove non-essential files, without interaction.
junk FILE                   *Move FILE to ~/junk instead of removing it.
find. FILE(S)               *Search current dir and its subdirs for FILE(S).
touch FILE                  Update modification date/time of FILE.
file FILE                   Find out the type of FILE.
gzip                        Compress or expand files.
zip                         Compress or expand files.
compress                    Compress or expand files.
tar                         Archive a directory into a file, or expand such a file.
targz DIRECTORY             *Pack DIRECTORY into archive file *.tgz
untargz ARCHIVE.tgz         *Unpack *.tgz archive into a directory.


more FILE                   Display contents of FILE, page by page.
less FILE                   Display contents of FILE, page by page.
cat FILE                    Display a file. (For very short files.)
head FILE                   Display first lines of FILE.
tail FILE                   Display last lines of FILE.

pico FILE                   Edit FILE using a user-friendly editor.
nano FILE                   Edit FILE using a user-friendly editor.
kwrite FILE                 Edit FILE using a user-friendly editor under X windows.
gedit FILE                  Edit FILE using a user-friendly editor under X windows.
emacs FILE                  Edit FILE using a powerful editor.
vim FILE                    Edit FILE using a powerful editor with cryptic syntax.
aspell -c FILE              Check spelling in text-file FILE.
ispell FILE                 *Check spelling in text-file FILE.

cat FILE1 FILE2 > NEW       Append FILE1 and FILE2 creating new file NEW.
cat FILE1 >> FILE2          Append FILE1 at the end of FILE2.

sort FILE > NEWFILE         Sort lines of FILE alphabetically and put them in NEWFILE.

grep STRING FILE(S)         Display lines of FILE(S) which contain STRING.
grep. STRING FILE(S)        *Similar as above, but better.
wc FILE(S)                  Count characters, words and lines in FILE(S).
diff FILE1 FILE2 | more     Show differences between two versions of a file.

filter FILE NEWFILE         *Filter out strange characters from FILE.
COMMAND | cut -b 1-9,15     Remove sections from each line.
COMMAND | uniq              Omit repeated lines.

lpr FILE                    In Hawk153B, print FILE from a workstation.
lprint1 FILE                *Print text-file on local printer; see help printing
lprint2 FILE                *Print text-file on local printer; see help printing


javac CLASSNAME.java        Compile a Java program.
java CLASSNAME              Run a Java program.
javadoc CLASSNAME.java      Create an html documentation file for CLASSNAME.
appletviewer CLASSNAME      Run an applet.

lisp                        *Listener of LISP programming language.

prolog                      *Listener of Prolog programming language.
python                      Listener of Python programming language.
cc -g -Wall -o FILE FILE.c  Compile C source FILE.c into executable FILE.
gcc -g -Wall -o FILE FILE.c Compile C source FILE.c into executable FILE.
c++ -g -Wall -o FIL FIL.cxx Compile C++ source FIL.cxx into executable FIL.
g++ -g -Wall -o FIL FIL.cxx Compile C++ source FIL.cxx into executable FIL.
gdb EXECUTABLE              Start debugging a C/C++ program.
make FILE                   Compile and link C/C++ files specified in makefile
m                           *Same as make but directs messages to a log file.
c-work                      *Repeatedly edit-compile-run a C program.
lynx                        Web browser (for text-based terminals).
firefox                     Web browser.
konqueror                   Web browser.
BROWSER                     Browse the Internet.
BROWSER FILE.html           Display a local html file.
BROWSER FILE.pdf            Display a local pdf file.

mutt                        Text-based e-mail manager.
pine                        Text-based e-mail manager (on some systems).

ssh HOST                    Open interactive session on HOST using secure shell.
sftp HOST                   Open sftp (secure file transfer) connection to HOST.
rsync ARGUMENTS             Synchronize directories on local and remote host.
Notes: A process is a run of a program;
One program can be used to create many concurrent processes.
A job may consist of several processes with pipes and redirections.
Processes are managed by the kernel.
Jobs are managed by a shell.

CTRL-Z                      Suspend current foreground process.
fg                          Bring job suspended by CTRL-Z to the foreground.
bg JOB                      Restart suspended JOb in the background.
ps                          List processes.
ps.                         *List processes.
jobs                        List current jobs (A job may involve many processes).
kill PROCESS                Kill PROCESS (however some processes may resist).
ctrl-C                      Kill the foreground process (but it may resist).
kill -9 PROCESS             Kill PROCESS (no process can resist.)
kill. PROCESS               *Kill PROCESS; same as kill -9.
COMMAND &                   Run COMMAND in the background.
env | sort | more           List all the environment variables with values.
echo $VARIABLE              List the value of VARIABLE.
unset VARIABLE              Remove VARIABLE.
export VARIABLE=VALUE       Create environment variable VARIABLE and set to VALUE.

exit                        Exit from any shell.
logout                      Exit from the login shell and terminate session.

svn                         Version control system.

xterm                       A shell window under X-windows.
xcalc                       A calculator under X-windows.
xclock                      A clock under X windows.
xeyes                       They watch you work and report to the Boss 🙂

date                        Display date and time.

clear                       Clear shell window.
xrefresh                    Refresh X-windows.
reset                       *Reset session.
setup-account               *Set up or reset your account (Dr. Plaza’s customizations)
Commands and directory names related to csc219 have 219 as a suffix.
By changing the suffix you will obtain commands for other courses.
ls $csc219                  *List files related to csc219.
cd $csc219                  *change into instructor’s public directory for csc219.
cp $csc219/FILE .           *Copy FILE related to csc219 to the current directory
cp -r $csc219/SUBDIR .      *Copy SUBDIR of csc219 to the current directory.
submit                      *Submit a directory with files for an assignment.
grades                      *See your grades. Used in some courses only.

Note: not all of these are actually part of UNIX itself, and you may not find them on all UNIX machines. But they can all be used on turing in essentially the same way, by typing the command and hitting return. Note that some of these commands are different on non-Solaris machines – see SunOS differences.

If you’ve made a typo, the easiest thing to do is hit CTRL-u to cancel the whole line. But you can also edit the command line (see the guide to More UNIX).
UNIX is case-sensitive.


  • ls — lists your files
    ls -l — lists your files in ‘long format’, which contains lots of useful information, e.g. the exact size of the file, who owns the file and who has the right to look at it, and when it was last modified.
    ls -a — lists all files, including the ones whose filenames begin in a dot, which you do not always want to see.
    There are many more options, for example to list files by size, by date, recursively etc.
  • more filename — shows the first part of a file, just as much as will fit on one screen. Just hit the space bar to see more or q to quit. You can use /pattern to search for a pattern.
  • emacs filename — is an editor that lets you create and edit a file. See the emacs page.
  • mv filename1 filename2 — moves a file (i.e. gives it a different name, or moves it into a different directory (see below)
  • cp filename1 filename2 — copies a file
  • rm filename — removes a file. It is wise to use the option rm -i, which will ask you for confirmation before actually deleting anything. You can make this your default by making an alias in your .cshrc file.
  • diff filename1 filename2 — compares files, and shows where they differ
  • wc filename — tells you how many lines, words, and characters there are in a file
  • chmod options filename — lets you change the read, write, and execute permissions on your files. The default is that only you can look at them and change them, but you may sometimes want to change these permissions. For example, chmod o+r filename will make the file readable for everyone, and chmod o-r filename will make it unreadable for others again. Note that for someone to be able to actually look at the file the directories it is in need to be at least executable. See help protection for more details.
  • File Compression
    • gzip filename — compresses files, so that they take up much less space. Usually text files compress to about half their original size, but it depends very much on the size of the file and the nature of the contents. There are other tools for this purpose, too (e.g. compress), but gzip usually gives the highest compression rate. Gzip produces files with the ending ‘.gz’ appended to the original filename.
    • gunzip filename — uncompresses files compressed by gzip.
    • gzcat filename — lets you look at a gzipped file without actually having to gunzip it (same as gunzip -c). You can even print it directly, using gzcat filename | lpr
  • printing
    • lpr filename — print. Use the -P option to specify the printer name if you want to use a printer other than your default printer. For example, if you want to print double-sided, use ‘lpr -Pvalkyr-d’, or if you’re at CSLI, you may want to use ‘lpr -Pcord115-d’. See ‘help printers’ for more information about printers and their locations.
    • lpq — check out the printer queue, e.g. to get the number needed for removal, or to see how many other files will be printed before yours will come out
    • lprm jobnumber — remove something from the printer queue. You can find the job number by using lpq. Theoretically you also have to specify a printer name, but this isn’t necessary as long as you use your default printer in the department.
    • genscript — converts plain text files into postscript for printing, and gives you some options for formatting. Consider making an alias like alias ecop ‘genscript -2 -r \!* | lpr -h -Pvalkyr’ to print two pages on one piece of paper.
    • dvips filename — print .dvi files. You can use dviselect to print only selected pages.


Directories, like folders on a Macintosh, are used to group files together in a hierarchical structure.

  • mkdir dirname — make a new directory
  • cd dirname — change directory. You basically ‘go’ to another directory, and you will see the files in that directory when you do ‘ls’. You always start out in your ‘home directory’, and you can get back there by typing ‘cd’ without arguments. ‘cd ..’ will get you one level up from your current position. You don’t have to walk along step by step – you can make big leaps or avoid walking around by specifying pathnames.
  • pwd — tells you where you currently are.

Finding things

  • ff — find files anywhere on the system. This can be extremely useful if you’ve forgotten in which directory you put a file, but do remember the name. In fact, if you use ff -p you don’t even need the full name, just the beginning. This can also be useful for finding other things on the system, e.g. documentation.
  • grep string filename(s) — looks for the string in the files. This can be useful a lot of purposes, e.g. finding the right file among many, figuring out which is the right version of something, and even doing serious corpus work. grep comes in several varieties (grepegrep, and fgrep) and has a lot of very flexible options. Check out the man pages if this sounds good to you.

About other people

  • w — tells you who’s logged in, and what they’re doing. Especially useful: the ‘idle’ part. This allows you to see whether they’re actually sitting there typing away at their keyboards right at the moment.
  • who — tells you who’s logged on, and where they’re coming from. Useful if you’re looking for someone who’s actually physically in the same building as you, or in some other particular location.
  • finger username — gives you lots of information about that user, e.g. when they last read their mail and whether they’re logged in. Often people put other practical information, such as phone numbers and addresses, in a file called .plan. This information is also displayed by ‘finger’.
  • last -1 username — tells you when the user last logged on and off and from where. Without any options, last will give you a list of everyone’s logins.
  • talk username — lets you have a (typed) conversation with another user
  • write username — lets you exchange one-line messages with another user
  • elm — lets you send e-mail messages to people around the world (and, of course, read them). It’s not the only mailer you can use, but the one we recommend. See the elm page, and find out about the departmental mailing lists (which you can also find in /user/linguistics/helpfile).

About your (electronic) self

  • whoami — returns your username. Sounds useless, but isn’t. You may need to find out who it is who forgot to log out somewhere, and make sure *you* have logged out.
  • finger & .plan files
    of course you can finger yourself, too. That can be useful e.g. as a quick check whether you got new mail. Try to create a useful .plan file soon. Look at other people’s .plan files for ideas. The file needs to be readable for everyone in order to be visible through ‘finger’. Do ‘chmod a+r .plan’ if necessary. You should realize that this information is accessible from anywhere in the world, not just to other people on turing.
  • passwd — lets you change your password, which you should do regularly (at least once a year). See the LRB guide and/or look at help password.
  • ps -u yourusername — lists your processes. Contains lots of information about them, including the process ID, which you need if you have to kill a process. Normally, when you have been kicked out of a dialin session or have otherwise managed to get yourself disconnected abruptly, this list will contain the processes you need to kill. Those may include the shell (tcsh or whatever you’re using), and anything you were running, for example emacs or elm. Be careful not to kill your current shell – the one with the number closer to the one of the ps command you’re currently running. But if it happens, don’t panic. Just try again 🙂 If you’re using an X-display you may have to kill some X processes before you can start them again. These will show only when you use ps -efl, because they’re root processes.
  • kill PID — kills (ends) the processes with the ID you gave. This works only for your own processes, of course. Get the ID by using ps. If the process doesn’t ‘die’ properly, use the option -9. But attempt without that option first, because it doesn’t give the process a chance to finish possibly important business before dying. You may need to kill processes for example if your modem connection was interrupted and you didn’t get logged out properly, which sometimes happens.
  • quota -v — show what your disk quota is (i.e. how much space you have to store files), how much you’re actually using, and in case you’ve exceeded your quota (which you’ll be given an automatic warning about by the system) how much time you have left to sort them out (by deleting or gzipping some, or moving them to your own computer).
  • du filename — shows the disk usage of the files and directories in filename (without argument the current directory is used). du -s gives only a total.
  • last yourusername — lists your last logins. Can be a useful memory aid for when you were where, how long you’ve been working for, and keeping track of your phonebill if you’re making a non-local phonecall for dialling in.

Connecting to the outside world

  • nn — allows you to read news. It will first let you read the news local to turing, and then the remote news. If you want to read only the local or remote news, you can use nnl or nnr, respectively. To learn more about nn type nn, then \tty{:man}, then \tty{=.*}, then \tty{Z}, then hit the space bar to step through the manual. Or look at the man page. Or check out the hypertext nn FAQ – probably the easiest and most fun way to go.
  • rlogin hostname — lets you connect to a remote host
  • telnet hostname — also lets you connect to a remote host. Use rlogin whenever possible.
  • ftp hostname — lets you download files from a remote host which is set up as an ftp-server. This is a common method for exchanging academic papers and drafts. If you need to make a paper of yours available in this way, you can (temporarily) put a copy in /user/ftp/pub/TMP. For more permanent solutions, ask Emma. The most important commands within ftp are get for getting files from the remote machine, and put for putting them there (mget and mput let you specify more than one file at once). Sounds straightforward, but be sure not to confuse the two, especially when your physical location doesn’t correspond to the direction of the ftp connection you’re making. ftp just overwrites files with the same filename. If you’re transferring anything other than ASCII text, use binary mode.
  • lynx — lets you browse the web from an ordinary terminal. Of course you can see only the text, not the pictures. You can type any URL as an argument to the G command. When you’re doing this from any Stanford host you can leave out the .stanford.edu part of the URL when connecting to Stanford URLs. Type H at any time to learn more about lynx, and Q to exit.

Miscellaneous tools

  • webster word — looks up the word in an electronic version of Webster’s dictionary and returns the definition(s)
  • date — shows the current date and time.
  • cal — shows a calendar of the current month. Use e.g., ‘cal 10 1995’ to get that for October 95, or ‘cal 1995’ to get the whole year.

You can find out more about these commands by looking up their manpages:
man commandname — shows you the manual page for the command

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