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 Unix Commands
Basic UNIX commands

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 (i.e. files produced by LaTeX). You can use dviselect to print only selected pages. See the LaTeX page for more information about how to save paper when printing drafts.


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 (grep, egrep, 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 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


More UNIX Commands

I have noticed that the overwhelming majority of visitors come to this page via a Lycos search. This page is probably *not* what you're looking for - see the links at the bottom of this page for more useful information!

  • jobs --- lists your currently active jobs (those that you put in the background) and their job numbers. Useful to determine which one you want to foreground if you have lots of them.

  • bg --- background a job after suspending it.

  • fg %jobnumber --- foreground a job

  • !! --- repeat the previous command (but CTRL-p, is safer, because you have hit return in addition)

  • !pattern --- repeat the last command that starts with pattern

  • echo $VARIABLE --- shows the value of an environment variable

  • setenv --- lets you set environment variables. For example, if you typed a wrong value for the TERM variable when logging in, you don't have to log out and start over, but you can just do setenv TERM vt100 (or whatever). To see what all your environment variables are set to, type env. The one that you're most likely to have to set is the DISPLAY variable, when using an X-display.

  • unset VAR --- lets you un-set environment variables. Useful, for example, if you've usually set autologout but want to stay logged on for a while without typing for some reason, or if you set the DISPLAY variable automatically but want to avoid opening windows for some reason.

  • source filename --- you need to source your dotfiles after making changes for them to take effect (or log off and in again)

  • load --- will show you the load average graphically

  • ispell filename --- will check the spelling in your file. If you're running it on a LaTeX file use the -T option to tell it to ignore the LaTeX commands. You can create and use your own dictionary to avoid having it tell you that your own name, those of fellow linguists, and linguistics terminology are a typos in every paper you write.

  • weblint --- checks the syntax of html files

  • latex2html --- translates LaTeX files into HTML

  • wn word option --- lets you access the WordNet database and display, for example, synonyms, hypernyms, or hyponyms, depending on the option you select

Command editing in the tcsh


These things are the same as in emacs:

Backspace --- delete previous character
CTRL-d --- delete next character
CTRL-k --- delete rest of line
CTRL-a --- go to start of line
CTRL-e --- go to end of line
CTRL-b --- go backwards without deleting
CTRL-f --- go forward without deleting



Other useful things

TAB --- complete filename or command up to the point of uniqueness

CTRL-u --- cancel whole line

CTRL-p --- show the last command typed, then the one before that, etc.

(you can also use the cursor up key for this)

CTRL-n --- go forwards in the history of commands

(you can also use the cursor down key for this)

CTRL-c --- cancel the processes after it has started

CTRL-z --- suspend a running process (e.g. in order to do something else in between)

you can then put the process in the background with bg

CTRL-l --- redraws the screen

| (piping) --- Lets you execute any number of commands in a sequence.

The second command will be executed once the first is done, and so forth, using the previous command's output as input. You can achieve the same effect by putting the output in a file and giving the filename as an argument to the second command, but that would be much more complicated, and you'd have to remember to remove all the junkfiles afterwards. Some examples that show the usefulness of this:
ls | more --- will show you one screenful at a time, which is useful with any command that will produce a lot of output, e.g. also ps -aux
man ls | grep time --- checks whether the man page for ls has something to say about listing files by time - very useful when you have a suspicion some command may be capable of doing what you want, but you aren't sure.
ls -lR | grep dvi --- will show you all your dvi files - useful to solve disk space problems, since they're large and usually can be deleted.



Following are basic commands on the shared UNIX workstations (Cardinal, Tree, Junior, Power, Wisdom, and remote workstations).
Introductory Information about UNIX
UNIX is a computer operating system, like DOS for PCs. An operating system consists of commands that let you manage information in the form of files or run programs that perform tasks such as word processing, email, or data analysis.
A UNIX file is a collection of information stored on disk, be it the text of a document, data for statistical analysis, or the executable code for a program. A file is referenced by a name. A filename in UNIX can consist of any combination of characters on the keyboard except for the space bar and all of the following: * ? ! | \ / ' " { } < > ; , ^ ( ) $ ~. These characters cannot be used in filenames because they have special meaning to the shell. For example, the first two symbols are used as "wildcard" characters when you're issuing commands: the * will match any string of characters in a filename, whereas the ? matches any single character.
How to Issue Commands in UNIX
The UNIX environment is interactive. When you type a command at the keyboard and then press the Enter or Return key, UNIX immediately begins to act on the command. More accurately, UNIX interprets the command using a special program of its own called the shell. The default shell is tcsh. All shells produce a shell prompt to let you know that UNIX is awaiting your next command. The shell prompt has the form host:~>, where host is the name of the UNIX system you are using (e.g. Elaine38:~> or Cardinal:~>). Whenever you see this prompt, you know that the UNIX shell is ready for your next command.
UNIX is case-sensitive. That is, UNIX distinguishes between upper and lower case letters in the names of files and programs. Thus, while ls is a valid UNIX command, LS is not. Login names and passwords are also case-sensitive.
Some programs, such as Pico, have their own commands that you type within the program rather than at the UNIX shell prompt. However, the shell prompt reappears whenever you exit such programs.
Basic File Commands
These are typed at the shell prompt host:~>.

List the files in the current directory
List all the files in the current directory, even the hidden ones
As above, but indicate sub-directories by appending a backslash (/) to their name
Make a copy of FILE1 and call the copy FILE2
Rename a file from old name FILE1 to new name FILE2
Move a file from it's present directory into another directory (DIR)
Remove or delete FILE
more FILE
Display the contents of FILE, pausing after each screenful

Whenever you see something like the above at the bottom of your screen, you can:
press the space bar
To see the next screenful of text
type b
To go back one screenful
type q
To quit the listing of text and return to the UNIX shell prompt

Correcting Typing Mistakes: (at the Shell Prompt)

Delete or Backspace
Erase the last character you typed
Delete the last line you typed

Basic Directory Commands
These are typed at the shell prompt host:~>.
In UNIX, your files are organized in directories and subdirectories. When you first log in to your account, you are placed in your home directory which you can refer to with the character ~.

cd DIR
Go to the directory called DIR
Go to the directory above the current directory
mkdir DIR
Create a new directory called DIR
rmdir DIR
Remove the directory DIR (must be empty first; if not, use rm  -r)
cd or cd ~
Go to your home directory
mv DIR1 DIR2
Move or rename a directory from old name DIR1 to new name DIR2

Use the / character to separate directory and file names when specifying a path.
You can print UNIX files and mail messages to your own printer and a network printer. The latter is easier, but requires that you walk to the network printer to pick up your output.
Printing On a Sweet Hall Printer
To print a UNIX text or PostScript file, type the following command at the system prompt: lpr -PNAME FILE ->
where NAME is the name of the printer, e.g.,polya0.
Printing to Your Own Printer
To print a UNIX file on your own printer, you must first "download" it to your desktop computer. Exactly how you do this depends on which communication package you use, as well as which type of computer you have. These instructions apply only to PCs (and compatibles) that are running under DOS, are linked to SUNet, and have the ftp protocol installed.
At the DOS prompt (assumed here to be C:\>), enter:

Connects your PC to HOSTNAME
(username) userid
Your account on the host
Password: xxxxxx
Replace xxxxxx with your password
ftp> get FILENAME
ftp> quit
Exit ftp and go to DOS
C:\> copy FILENAME lpt1
Prints FILENAME on lpt1

Useful Commands

Ends your work on the UNIX system
Ctrl-l or clear
Clears the screen
Stops the program currently running
Retrieves the last shell command you typed
Pauses the currently running program
Looks up the UNIX command COMMAND in the online manual pages
find . -name FILE -print
Finds all paths containing FILE in the current directory or below it
Searches for and displays all lines in file that contain PATTERN (case insensitive)
Displays login/email status of a user at another host
Lists background jobs started during your current login session
Lists all jobs (background and foreground) started during your login session
Displays disk usage in kbytes by directory, starting in the current directory and working down
du -s
Displays total disk usage
fs listquota
Displays your current disk space usage and quota in kbytes
telnet ADDRESS
Logs on to another machine on the Internet on which you have an account
Begins a file transfer session with another computer on the Internet
Counts the lines, words, and characters in FILE
spell FILE
Reports possible misspelled words in FILE
webster WORD | more
Looks up a word via the online version of Webster's dictionary

UNIX Shell Short Cuts
The UNIX shell keeps a record of the commands you type during your login session. Here are a few commands that take advantage of this history facility. All are typed at the shell prompt host:~>.

List all commands typed so far (default maximum number=20)
Repeat the last command
Repeat command n from the history list
Repeat last command beginning with PATTERN
Repeat last command but replace PATTERN1 (usually a typo) with PATTERN2 (the correction)

Unix Command Summary


           cat --- for creating and displaying short files

           chmod --- change permissions

           cd --- change directory

           cp --- for copying files

           date --- display date

           echo --- echo argument

           ftp --- connect to a remote machine to download or upload files

           grep --- search file

           head --- display first part of file

           ls --- see what files you have

           lpr --- standard print command (see also print )

           more --- use to read files

           mkdir --- create directory

           mv --- for moving and renaming files

           ncftp --- especially good for downloading files via anonymous ftp.

           print --- custom print command (see also lpr )

           pwd --- find out what directory you are in

           rm --- remove a file

           rmdir --- remove directory

           rsh --- remote shell

           setenv --- set an environment variable

           sort --- sort file

           tail --- display last part of file

           tar --- create an archive, add or extract files

           telnet --- log in to another machine

           wc --- count characters, words, lines


This is one of the most flexible Unix commands. We can use to create, view and concatenate files. For our first example we create a three-item English-Spanish dictionary in a file called "dict."

   % cat >dict
     red rojo
     green verde
     blue azul

<control-D> stands for "hold the control key down, then tap 'd'". The symbol > tells the computer that what is typed is to be put into the file dict. To view a file we use cat in a different way:

   % cat dict
     red rojo
     green verde
     blue azul

If we wish to add text to an existing file we do this:

   % cat >>dict
     white blanco
     black negro

Now suppose that we have another file tmp that looks like this:

   % cat tmp
     cat gato
     dog perro

Then we can join dict and tmp like this:

   % cat dict tmp >dict2

We could check the number of lines in the new file like this:

   % wc -l dict2

The command wc counts things --- the number of characters, words, and line in a file.


This command is used to change the permissions of a file or directory. For example to make a file essay.001 readable by everyone, we do this:

   % chmod a+r essay.001

To make a file, e.g., a shell script mycommand executable, we do this

   % chmod +x mycommand

Now we can run mycommand as a command.

To check the permissions of a file, use ls -l . For more information on chmod, use man chmod.


Use cd to change directory. Use pwd to see what directory you are in.

   % cd english
   % pwd
   % /u/ma/jeremy/english
   % ls
novel poems
   % cd novel
   % pwd
   % /u/ma/jeremy/english/novel
   % ls
ch1 ch2 ch3 journal scrapbook
   % cd ..
   % pwd
   % /u/ma/jeremy/english
   % cd poems
   % cd
   % /u/ma/jeremy

Jeremy began in his home directory, then went to his english subdirectory. He listed this directory using ls , found that it contained two entries, both of which happen to be diretories. He cd'd to the diretory novel, and found that he had gotten only as far as chapter 3 in his writing. Then he used cd .. to jump back one level. If had wanted to jump back one level, then go to poems he could have said cd ../poems. Finally he used cd with no argument to jump back to his home directory.


Use cp to copy files or directories.

   % cp foo foo.2

This makes a copy of the file foo.

   % cp ~/poems/jabber .

This copies the file jabber in the directory poems to the current directory. The symbol "." stands for the current directory. The symbol "~" stands for the home directory.


Use this command to check the date and time.

   % date
Fri Jan  6 08:52:42 MST 1995


The echo command echoes its arguments. Here are some examples:

   % echo this
   % echo $EDITOR
   % echo $PRINTER

Things like PRINTER are so-called environment variables. This one stores the name of the default printer --- the one that print jobs will go to unless you take some action to change things. The dollar sign before an environment variable is needed to get the value in the variable. Try the following to verify this:

   % echo PRINTER


Use ftp to connect to a remote machine, then upload or download files. See also: ncfpt

Example 1: We'll connect to the machine, then change director to mystuff, then download the file homework11:

   % ftp solitude
     Connected to
     220 FTP server (Version wu-2.4(11) Mon Apr 18 17:26:33 MDT 1994) ready.
   Name (solitude:carlson): jeremy
     331 Password required for jeremy.
     230 User jeremy logged in.
   ftp> cd mystuff
     250 CWD command successful.
   ftp> get homework11
   ftp> quit

Example 2: We'll connect to the machine, then change director to mystuff, then upload the file collected-letters:

   % ftp solitude
     Connected to
     220 FTP server (Version wu-2.4(11) Mon Apr 18 17:26:33 MDT 1994) ready.
   Name (solitude:carlson): jeremy
     331 Password required for jeremy.
     230 User jeremy logged in.
   ftp> cd mystuff
     250 CWD command successful.
   ftp> put collected-letters
   ftp> quit

The ftp program sends files in ascii (text) format unless you specify binary mode:

   ftp> binary
   ftp> put foo
   ftp> ascii
   ftp> get bar

The file foo was transferred in binary mode, the file bar was transferred in ascii mode.


Use this command to search for information in a file or files. For example, suppose that we have a file dict whose contents are

   red rojo
   green verde
   blue azul
   white blanco
   black negro

Then we can look up items in our file like this;

   % grep red dict
     red rojo
   % grep blanco dict
     white blanco
   % grep brown dict

Notice that no output was returned by grep brown. This is because "brown" is not in our dictionary file.

Grep can also be combined with other commands. For example, if one had a file of phone numbers named "ph", one entry per line, then the following command would give an alphabetical list of all persons whose name contains the string "Fred".

   % grep Fred ph | sort
     Alpha, Fred: 333-6565
     Beta, Freddie: 656-0099
     Frederickson, Molly: 444-0981
     Gamma, Fred-George: 111-7676
     Zeta, Frederick: 431-0987

The symbol "|" is called "pipe." It pipes the output of the grep command into the input of the sort command.

For more information on grep, consult

   % man grep


Use this command to look at the head of a file. For example,

   % head essay.001

displays the first 10 lines of the file essay.001 To see a specific number of lines, do this:

   % head -20 essay.001

This displays the first 20 lines of the file.


Use ls to see what files you have. Your files are kept in something called a directory.

   % ls
     foo       letter2
     foobar    letter3
     letter1   maple-assignment1

Note that you have six files. There are some useful variants of the ls command:

   % ls l*
     letter1 letter2 letter3

Note what happened: all the files whose name begins with "l" are listed. The asterisk (*) is the " wildcard" character. It matches any string.


This is the standard Unix command for printing a file. It stands for the ancient "line printer." See

   % man lpr

for information on how it works. See print for information on our local intelligent print command.


Use this command to create a directory.

   % mkdir essays

To get "into" this directory, do

   % cd essays

To see what files are in essays, do this:

   % ls

There shouldn't be any files there yet, since you just made it. To create files, see cat or emacs.


More is a command used to read text files. For example, we could do this:

   % more poems

The effect of this to let you read the file "poems ". It probably will not fit in one screen, so you need to know how to "turn pages". Here are the basic commands:

  • q --- quit more
  • spacebar --- read next page
  • return key --- read next line
  • b --- go back one page

For still more information, use the command man more.


Use this command to change the name of file and directories.

   % mv foo foobar

The file that was named foo is now named foobar


Use ncftp for anonymous ftp --- that means you don't have to have a password.

   % ncftp
     Connected to
   > get jokes.txt

The file jokes.txt is downloaded from the machine


This is a moderately intelligent print command.

   % print foo
   % print
   % print manuscript.dvi

In each case print does the right thing, regardless of whether the file is a text file (like foo ), a postcript file (like, or a dvi file (like manuscript.dvi. In these examples the file is printed on the default printer. To see what this is, do

   % print

and read the message displayed. To print on a specific printer, do this:

   % print foo jwb321
   % print jwb321
   % print manuscript.dvi jwb321

To change the default printer, do this:

   % setenv PRINTER jwb321


Use this command to find out what directory you are working in.

   % pwd
   % cd homework
   % pwd
   % ls
assign-1 assign-2 assign-3
   % cd
   % pwd

Jeremy began by working in his "home" directory. Then he cd 'd into his homework subdirectory. Cd means " change directory". He used pwd to check to make sure he was in the right place, then used ls to see if all his homework files were there. (They were). Then he cd'd back to his home directory.


Use rm to remove files from your directory.

   % rm foo
     remove foo? y
   % rm letter*
     remove letter1? y
     remove letter2? y
     remove letter3? n

The first command removed a single file. The second command was intended to remove all files beginning with the string "letter." However, our user (Jeremy?) decided not to remove letter3.


Use this command to remove a directory. For example, to remove a directory called "essays", do this:

   % rmdir essays

A directory must be empty before it can be removed. To empty a directory, use rm.


Use this command if you want to work on a computer different from the one you are currently working on. One reason to do this is that the remote machine might be faster. For example, the command

   % rsh solitude

connects you to the machine solitude. This is one of our public workstations and is fairly fast.

See also: telnet


   % echo $PRINTER
   % setenv PRINTER myprinter
   % echo $PRINTER


Use this commmand to sort a file. For example, suppose we have a file dict with contents

red rojo
green verde
blue azul
white blanco
black negro

Then we can do this:

   % sort dict
     black negro
     blue azul
     green verde
     red rojo
     white blanco

Here the output of sort went to the screen. To store the output in file we do this:

   % sort dict >dict.sorted 

You can check the contents of the file dict.sorted using cat , more , or emacs


Use this command to look at the tail of a file. For example,

   % head essay.001

displays the last 10 lines of the file essay.001 To see a specific number of lines, do this:

   % head -20 essay.001

This displays the last 20 lines of the file.


Use create compressed archives of directories and files, and also to extract directories and files from an archive. Example:

   % tar -tvzf foo.tar.gz

displays the file names in the compressed archive foo.tar.gz while

   % tar -xvzf foo.tar.gz

extracts the files.


Use this command to log in to another machine from the machine you are currently working on. For example, to log in to the machine "solitude", do this:

   % telnet solitude

See also: rsh.


Use this command to count the number of characters, words, and lines in a file. Suppose, for example, that we have a file dict with contents

red rojo
green verde
blue azul
white blanco
black negro

Then we can do this

   % wc dict
     5      10      56 tmp

This shows that dict has 5 lines, 10 words, and 56 characters.

The word count command has several options, as illustrated below:

   % wc -l dict
     5 tmp
   % wc -w dict
     10 tmp
   % wc -c dict
     56 tmp


Environment Control
Command                     Description
 cd d                         Change to directory d
 mkdir d                      Create new directory d
 rmdir d                      Remove directory d
 mv f1 [f2...] d              Move file f to directory d
 mv d1 d2                     Rename directory d1 as d2
 passwd                       Change password
 alias name1 name2            Create command alias (csh/tcsh)
 alias name1="name2"          Create command alias (ksh/bash)
 unalias name1[na2...]        Remove command alias na
 ssh nd                       Login securely to remote node
 exit                         End terminal session
 setenv name v               Set env var to value v (csh/tcsh)
 export name="v"              set environment variable to value v (ksh/bash)


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