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 turingin 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.

Files

• 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

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 (mgetand 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.

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FREEENGINEER.ORG
Learn UNIX in 10 minutes. Version 1.3
Preface
This is something that I had given out to students (CAD user training) in years past.
The purpose was to have on one page the basics commands for getting started using
the UNIX shell (so that they didn't call me asking what to do the first time someone
gave them a tape).
This document is copyrighted but freely redistributable under the terms of the GFDL .
Have an idea for this page?
Send me patches, comments, corrections, about whatever you think is wrong or should be
included. I am always happy to hear from you. Please include the word "UNIX" in your subject.
Sections:
Directories:
Moving around the file system:
Listing directory contents:
Changing file permissions and attributes
Moving, renaming, and copying files:
Viewing and editing files:
Shells
Environment variables
Interactive History
Filename Completion
Bash is the way cool shell.
Redirection:
Pipes:
Command Substitution
Searching for strings in files: The grep command
Searching for files : The find command
Reading and writing tapes, backups, and archives: The tar command
File compression: compress, gzip, and bzip2
Looking for help: The man and apropos commands
Basics of the vi editor
FAQs
******************************************************************************************
Basic UNIX Command Line (shell) navigation : Last revised May 17 2001
******************************************************************************************
Directories:
File and directory paths in UNIX use the forward slash "/"
to separate directory names in a path.
examples:
/ "root" directory
/usr directory usr (sub-directory of / "root" directory)
/usr/STRIM100 STRIM100 is a subdirectory of /usr
Moving around the file system:
pwd Show the "present working directory", or current directory.
cd Change current directory to your HOME directory.
cd /usr/STRIM100 Change current directory to /usr/STRIM100.
cd INIT Change current directory to INIT which is a sub-directory of the current
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directory.
cd .. Change current directory to the parent directory of the current directory.
cd $STRMWORK Change current directory to the directory defined by the environment
variable 'STRMWORK'.
cd ~bob Change the current directory to the user bob's home directory (if you have permission).
Listing directory contents:
ls list a directory
ls -l list a directory in long ( detailed ) format
for example:
$ ls -l
drwxr-xr-x 4 cliff user 1024 Jun 18 09:40 WAITRON_EARNINGS
-rw-r--r-- 1 cliff user 767392 Jun 6 14:28 scanlib.tar.gz
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
| | | | | | | | | | |
| | | | | owner group size date time name
| | | | number of links to file or directory contents
| | | permissions for world
| | permissions for members of group
| permissions for owner of file: r = read, w = write, x = execute -=no permission
type of file: - = normal file, d=directory, l = symbolic link, and others...
ls -a List the current directory including hidden files. Hidden files start
with "."
ls -ld * List all the file and directory names in the current directory using
long format. Without the "d" option, ls would list the contents
of any sub-directory of the current. With the "d" option, ls
just lists them like regular files.
Changing file permissions and attributes
chmod 755 file Changes the permissions of file to be rwx for the owner, and rx for
the group and the world. (7 = rwx = 111 binary. 5 = r-x = 101 binary)
chgrp user file Makes file belong to the group user.
chown cliff file Makes cliff the owner of file.
chown -R cliff dir Makes cliff the owner of dir and everything in its directory tree.
You must be the owner of the file/directory or be root before you can do any of these things.
Moving, renaming, and copying files:
cp file1 file2 copy a file
mv file1 newname move or rename a file
mv file1 ~/AAA/ move file1 into sub-directory AAA in your home directory.
rm file1 [file2 ...] remove or delete a file
rm -r dir1 [dir2...] recursivly remove a directory and its contents BE CAREFUL!
mkdir dir1 [dir2...] create directories
mkdir -p dirpath create the directory dirpath, including all implied directories in the path.
rmdir dir1 [dir2...] remove an empty directory
Viewing and editing files:
cat filename Dump a file to the screen in ascii.
more filename Progressively dump a file to the screen: ENTER = one line down
SPACEBAR = page down q=quit
less filename Like more, but you can use Page-Up too. Not on all systems.
vi filename Edit a file using the vi editor. All UNIX systems will have vi in some form.
emacs filename Edit a file using the emacs editor. Not all systems will have emacs.
head filename Show the first few lines of a file.
head -n filename Show the first n lines of a file.
tail filename Show the last few lines of a file.
tail -n filename Show the last n lines of a file.
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Shells
The behavior of the command line interface will differ slightly depending
on the shell program that is being used.
Depending on the shell used, some extra behaviors can be quite nifty.
You can find out what shell you are using by the command:
echo $SHELL
Of course you can create a file with a list of shell commands and execute it like
a program to perform a task. This is called a shell script. This is in fact the
primary purpose of most shells, not the interactive command line behavior.
Environment variables
You can teach your shell to remember things for later using environment variables.
For example under the bash shell:
export CASROOT=/usr/local/CAS3.0 Defines the variable CASROOT with the value
/usr/local/CAS3.0.
export LD_LIBRARY_PATH=$CASROOT/Linux/lib Defines the variable LD_LIBRARY_PATH with
the value of CASROOT with /Linux/lib appended,
or /usr/local/CAS3.0/Linux/lib
By prefixing $ to the variable name, you can evaluate it in any command:
cd $CASROOT Changes your present working directory to the value of CASROOT
echo $CASROOT Prints out the value of CASROOT, or /usr/local/CAS3.0
printenv CASROOT Does the same thing in bash and some other shells.
Interactive History
A feature of bash and tcsh (and sometimes others) you can use
the up-arrow keys to access your previous commands, edit
them, and re-execute them.
Filename Completion
A feature of bash and tcsh (and possibly others) you can use the
TAB key to complete a partially typed filename. For example if you
have a file called constantine-monks-and-willy-wonka.txt in your
directory and want to edit it you can type 'vi const', hit the TAB key,
and the shell will fill in the rest of the name for you (provided the
completion is unique).
Bash is the way cool shell.
Bash will even complete the name of commands and environment variables.
And if there are multiple completions, if you hit TAB twice bash will show
you all the completions. Bash is the default user shell for most Linux systems.
Redirection:
grep string filename > newfile Redirects the output of the above grep
command to a file 'newfile'.
grep string filename >> existfile Appends the output of the grep command
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to the end of 'existfile'.
The redirection directives, > and >> can be used on the output of most commands
to direct their output to a file.
Pipes:
The pipe symbol "|" is used to direct the output of one command to the input
of another.
For example:
ls -l | more This commands takes the output of the long format directory list command
"ls -l" and pipes it through the more command (also known as a filter).
In this case a very long list of files can be viewed a page at a time.
du -sc * | sort -n | tail
The command "du -sc" lists the sizes of all files and directories in the
current working directory. That is piped through "sort -n" which orders the
output from smallest to largest size. Finally, that output is piped through "tail"
which displays only the last few (which just happen to be the largest) results.
Command Substitution
You can use the output of one command as an input to another command in another way
called command substitution. Command substitution is invoked when by enclosing the
substituted command in backwards single quotes. For example:
cat `find . -name aaa.txt`
which will cat ( dump to the screen ) all the files named aaa.txt that exist in the current
directory or in any subdirectory tree.
Searching for strings in files: The grep command
grep string filename prints all the lines in a file that contain the string
Searching for files : The find command
find search_path -name filename
find . -name aaa.txt Finds all the files named aaa.txt in the current directory or
any subdirectory tree.
find / -name vimrc Find all the files named 'vimrc' anywhere on the system.
find /usr/local/games -name "*xpilot*"
Find all files whose names contain the string 'xpilot' which
exist within the '/usr/local/games' directory tree.
Reading and writing tapes, backups, and archives: The tar command
The tar command stands for "tape archive". It is the "standard" way to read
and write archives (collections of files and whole directory trees).
Often you will find archives of stuff with names like stuff.tar, or stuff.tar.gz. This
is stuff in a tar archive, and stuff in a tar archive which has been compressed using the
gzip compression program respectivly.
Chances are that if someone gives you a tape written on a UNIX system, it will be in tar format,
and you will use tar (and your tape drive) to read it.
Likewise, if you want to write a tape to give to someone else, you should probably use
tar as well.
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Tar examples:
tar xv Extracts (x) files from the default tape drive while listing (v = verbose)
the file names to the screen.
tar tv Lists the files from the default tape device without extracting them.
tar cv file1 file2
Write files 'file1' and 'file2' to the default tape device.
tar cvf archive.tar file1 [file2...]
Create a tar archive as a file "archive.tar" containing file1,
file2...etc.
tar xvf archive.tar extract from the archive file
tar cvfz archive.tar.gz dname
Create a gzip compressed tar archive containing everything in the directory
'dname'. This does not work with all versions of tar.
tar xvfz archive.tar.gz
Extract a gzip compressed tar archive. Does not work with all versions of tar.
tar cvfI archive.tar.bz2 dname
Create a bz2 compressed tar archive. Does not work with all versions of tar
File compression: compress, gzip, and bzip2
The standard UNIX compression commands are compress and uncompress. Compressed files have
a suffix .Z added to their name. For example:
compress part.igs Creates a compressed file part.igs.Z
uncompress part.igs Uncompresseis part.igs from the compressed file part.igs.Z.
Note the .Z is not required.
Another common compression utility is gzip (and gunzip). These are the GNU compress and
uncompress utilities. gzip usually gives better compression than standard compress,
but may not be installed on all systems. The suffix for gzipped files is .gz
gzip part.igs Creates a compressed file part.igs.gz
gunzip part.igs Extracts the original file from part.igs.gz
The bzip2 utility has (in general) even better compression than gzip, but at the cost of longer
times to compress and uncompress the files. It is not as common a utility as gzip, but is
becoming more generally available.
bzip2 part.igs Create a compressed Iges file part.igs.bz2
bunzip2 part.igs.bz2 Uncompress the compressed iges file.
Looking for help: The man and apropos commands
Most of the commands have a manual page which give sometimes useful, often more or less
detailed, sometimes cryptic and unfathomable discriptions of their usage. Some say they
are called man pages because they are only for real men.
Example:
man ls Shows the manual page for the ls command
You can search through the man pages using apropos
Example:
apropos build Shows a list of all the man pages whose discriptions contain the word "build"
Do a man apropos for detailed help on apropos.
Basics of the vi editor
Opening a file
vi filename
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Creating text
Edit modes: These keys enter editing modes and type in the text
of your document.
i Insert before current cursor position
I Insert at beginning of current line
a Insert (append) after current cursor position
A Append to end of line
r Replace 1 character
R Replace mode
<ESC> Terminate insertion or overwrite mode
Deletion of text
x Delete single character
dd Delete current line and put in buffer
ndd Delete n lines (n is a number) and put them in buffer
J Attaches the next line to the end of the current line (deletes carriage return).
Oops
u Undo last command
cut and paste
yy Yank current line into buffer
nyy Yank n lines into buffer
p Put the contents of the buffer after the current line
P Put the contents of the buffer before the current line
cursor positioning
^d Page down
^u Page up
:n Position cursor at line n
:$ Position cursor at end of file
^g Display current line number
h,j,k,l Left,Down,Up, and Right respectivly. Your arrow keys should also work if
if your keyboard mappings are anywhere near sane.
string substitution
:n1,n2:s/string1/string2/[g] Substitute string2 for string1 on lines
n1 to n2. If g is included (meaning global),
all instances of string1 on each line
are substituted. If g is not included,
only the first instance per matching line is
substituted.
^ matches start of line
. matches any single character
$ matches end of line
These and other "special characters" (like the forward slash) can be "escaped" with \
i.e to match the string "/usr/STRIM100/SOFT" say "\/usr\/STRIM100\/SOFT"
Examples:
:1,$:s/dog/cat/g Substitute 'cat' for 'dog', every instance
for the entire file - lines 1 to $ (end of file)
:23,25:/frog/bird/ Substitute 'bird' for 'frog' on lines
23 through 25. Only the first instance
on each line is substituted.
Saving and quitting and other "ex" commands
These commands are all prefixed by pressing colon (:) and then entered in the lower
left corner of the window. They are called "ex" commands because they are commands
of the ex text editor - the precursor line editor to the screen editor
vi. You cannot enter an "ex" command when you are in an edit mode (typing text onto the screen)
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Press <ESC> to exit from an editing mode.
:w Write the current file.
:w new.file Write the file to the name 'new.file'.
:w! existing.file Overwrite an existing file with the file currently being edited.
:wq Write the file and quit.
:q Quit.
:q! Quit with no changes.
:e filename Open the file 'filename' for editing.
:set number Turns on line numbering
:set nonumber Turns off line numbering
FAQs
The USENET FAQs should be the first place you look for an answer to specific questions.
You can find most of them at RTFM
The contents of this directory includes vi, bash, and comp.unix.questions FAQs.
Searching USENET archives are very useful too.
google.com has a USENET archive (formerly Deja.com's) .
Advanced Group Search rules.
This document was converted from plain text using Vim and
then hacked. Vim is the best version of the one true text editor: vi.
Copyright (c) 2000-2006
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
or any later version published by the Free Software Foundation;
with Invariant Section: Preface, with Front-Cover Texts, and with no
Back-Cover Texts. A copy of the license can be found on the GNU web site
here.
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You can find out more about these commands by looking up their manpages:
man commandname --- shows you the manual page for the command For further ways of obtaining help, look at the pages with electronic sources of informationand non-electronic sources.
More UNIX commands

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