| Command |
Action
|
Example
|
| |
Creates a temporary name (alias) for a Unix command. When you type alias-name, string is substituted and run in its place. Typically, you put alias commands in your .cshrc file. Aliases can be self-referential without causing infinite recursion, e.g.:
alias rm ‘rm -i’ |
alias alias_name string |
| |
To remove an alias |
unalias name |
| ansiprint |
Prints a file to a printer connected to your computer. |
ansiprint file |
| apropos |
Find a list of manual pages about a keyword. |
apropos keyword |
| Ar |
Create and maintain library archives |
|
| archie |
search the Archie database for a file on a FTP site |
archie file |
| asa |
Text Processing: Interpret carriage-control characters |
|
| assets |
Displays your account resources, use, and threshold. |
|
| At |
Process Management: Execute commands at a later time |
|
| awk |
Text Processing: Pattern scanning and processing language. awk is most commonly used to extract numbered fields from lines of text. For example, the following command prints the third word on each line: awk also supports more complicated scripting – see the manual page. |
awk '{print $5}' [file]
|
| basename |
File system: Return non-directory portion of a pathname |
|
| batch |
Process Management: Schedule commands to be executed in a batch queue |
|
| Bc |
A simple calculator; Arbitrary-precision arithmetic language. Uses integer arithmetic by default. For floating-point arithmetic, type “bc -l”. |
|
| |
Process Management: Places or runs job in the background. |
|
| break |
Shell programming: Exit from for, while, or until loop |
|
| cal |
Display a calendar of the current month. |
|
| |
Display a calendar of the given month and year. Note that the year must be fully qualified, for example, “2003” and not “03.” |
cal month year |
| |
File system: Concatenate and displays specified files |
cat file |
| |
Overwrites the file2 with the content of file1 |
cat file1>file2 |
| |
Append file1 to the end of file2 |
cat file1>>file2 |
| |
Creates a file, typing some text, and finishing by pressing ctrl-d at the start of a line. |
cat > file1 |
| Cc |
Compile a C program |
|
| Cd |
File system: Changes current directory to a different directory. |
cd directory |
| |
To change back to your home directory: |
cd |
| |
Directory abbreviations:
~ Home directory
.. Parent directory
. Current working directory |
|
| cflow |
C Programming : Generate a C-language flowgraph |
|
| chfn |
change your “Real Name” as seen on finger |
|
| chgrp |
File system: Change the file group ownership. Makes file belong to the group user. NOTE: You must be the owner of the file/directory or be root |
chgrp user file |
| chmod |
File system: Change the file modes/attributes/permissions NOTE: You must be the owner of the file/directory or be root |
chmod code file
chmod code directory |
| |
To keep a file private |
chmod 600 file |
| |
To give everyone read permission: |
chmod 664 file |
| chown |
File system: Change the file ownership NOTE: You must be the owner of the file/directory or be root |
chown new_own file |
|
Makes cliff(new_own) the owner of dir and everything in its directory tree. NOTE: You must be the owner of the file/directory or be root |
chown -R cliff dir |
| chsh |
change the shell you log into |
|
| cksum |
File system: Write file checksums and sizes |
|
| clear |
Clears terminal screen |
clear |
| cmp |
File system: Compare two files |
|
| comm |
Text Processing: Select or reject lines common to two files |
|
| command |
Shell programming: Execute a simple command |
command |
| |
Shell programming: Executes command1 in background |
Command1& |
| compress |
File system: Reduces the size of a file and adds .Z to the file’s name. |
compress file |
| |
To restore a compressed file: |
uncompress file.Z |
| continue |
Shell programming: Continue for, while, or until loop |
|
| Cp |
File system: Makes a copy of a file. |
cp file1 file2 |
| |
To copy a file into a different directory: |
cp file directory |
| |
To inquire before overwriting an existing file: |
cp -i file1 file2 |
|
To copy a directory and, recursively, its subdirectories |
cp -r dir1 dir2 |
|
To retain timestamp while copying |
cp -p |
| crontab |
Schedule periodic background work |
|
| csplit |
Text Processing: Split files based on context |
|
| ctags |
C Programming: Create a tags file |
|
| cut |
Shell programming: Cut out selected fields of each line of a file |
|
| cxref |
C Programming: Generate a C-language program cross-reference table |
|
| date |
Display the current local date and time. |
date |
| Dd |
File system: Convert and copy a file |
|
| delta |
Make a delta (change) to an SCCS file |
|
| Df |
File system: Report free disk space available on the system |
|
| |
print list of disks and current capacity (in kilobytes) |
df -k |
|
Text Processing: Compares two files and displays the differences. Here, shows differences between file1 and file2 |
diff file1 file2 |
| dirname |
File system: Return the directory portion of a pathname |
|
| dos2unix |
strips CR’s out of dos text files |
dos2unix <file> <new_file> |
| dot |
Shell programming: Execute commands in the current environment |
|
| Du |
File system: Estimate file space usage |
du |
|
Print size (in kilobytes) of current directory (“.”). Variations:
du -sk * prints sizes (in kilobytes) of all files and sub-directories
du -sk file prints size (in kilobytes) of file
du -sk dir prints sum of size (in kilobytes) of dir and its contents |
du -sk |
| dvips |
Print .dvi files (i.e. files produced by LaTeX). You can use dviselect to print only selected pages. |
dvips filename |
| echo |
Shell programming: Displays a line of text or
Write arguments to standard output. Note that the shell will expand variables in the line, e.g. ” echo $user ” will print the contents of the variable user. Use single quotes (e.g. ” echo '$user' “) if you want to prevent this. |
echo text |
|
Example: This command find out what shell you are using by the command |
echo $SHELL |
| Ed |
Text Processing: The standard text editor |
|
| elm |
Another email program |
|
| emacs |
Text editor: Edit a file using the emacs editor. Not all systems will have emacs. It’s Extremely versatile. In emacs, press ctrl-h, t for a tutorial. |
emacs filename |
| env |
Set the environment for command invocation |
|
| eval |
Shell programming: Construct command by concatenating arguments |
|
| Ex |
Text Processing: Text editor |
|
| exec |
Shell programming: Execute commands and open, close, or copy file descriptors |
|
| exit |
Shell programming: Exits from the current shell. Similar to logout, but can also be used in shell scripts. |
|
| expand |
Text Processing: Convert tabs to spaces |
|
| export |
Set the export attribute for variables |
|
| expr |
Shell programming: Evaluate arguments as an expression. Give it expressions on the command line. Make sure to put spaces around the numbers, e.g.
expr ‘2 + 2’ |
expr ‘expression‘
|
| false |
Shell programming: Return false value |
|
| Fc |
Process the command history list |
|
| 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. |
|
|
Process Management: Restarts a suspended job in the foreground. |
|
| File |
File system: Determine file type |
file files |
| find |
File system: Find the loation of file.1 in the directory and sub-directories. Variations:
find . -name “*pattern” -print finds all files that end with pattern.
find . -name file.1 -exec rm ‘{}’ ‘;’ removes all files named file.1. |
find . -name file.1 -print |
| finger |
Displays user information at the specified computer. |
finger userid@computer |
| |
To change your finger entry information: |
chfn |
| fold |
Text Processing: Filter for folding lines |
|
| fort77 |
C Programming: FORTRAN compiler |
|
| ftp |
Starts the file transfer program with a remote computer insecurely. This method does not use encryption, so there is a risk of your password and other data being spied on. It should be avoided wherever scp is available. |
ftp host_address |
| fuser |
Process Management: List process IDs of all processes that have one or more files open |
|
| gcc |
Compiles C source into a file named ‘a.out’. It compiles a C program with the GNU C-compiler |
gcc file.c |
| gencat |
Generate a formatted message catalog |
|
| 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. |
|
| getconf |
Get configuration values |
|
| getopts |
Shell programming: Parse utility options |
|
| gopher |
A Gopher database browser |
|
|
Finds lines in a file matching a character pattern. 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. |
grep -icvn pattern file |
| |
-i Ignores case
-c Lists count of lines that contain pattern
-v Lists all lines except those with pattern
-n Lists line number for each found pattern |
|
| gzip |
Compress the specified files. This turns filename into filename.gz, which is smaller.
Text files compress very well, but with binary data files you might not save much disk space |
gzip file...
|
| |
Uncompress the specified files.The opposite of the gzip command. |
gunzip file... |
| |
To 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 |
gzcat filename |
| hash |
Remember or report utility locations |
|
|
Text Processing: Displays the first ten lines of a file. |
head file |
| |
To display the first n number of lines |
head -n file |
| help |
Displays an online help note. |
help note |
| |
To display a list of help notes: |
help -l |
| history |
Displays a list of your most recent commands. |
history |
| |
To repeat the nth command from the list. (for example, type “!m” to repeat the last command that began with “m”) |
! n |
| |
To repeat your most recent command |
!! |
| hostname |
Show the name of the machine |
|
| iconv |
Text Processing: Codeset conversion |
|
| Id |
Return user identity |
|
| ipcrm |
Remove a message queue, semaphore set, or shared memory segment identifier |
|
| ipcs |
Report interprocess communication facilities status |
|
| Irc |
connect to Internet Relay Chat |
|
|
Process Management: Displays active jobs and their corresponding job numbers |
jobs |
| |
To start a job in the background: |
job & |
| |
To return a job to the foreground by the job number |
fg %number |
| |
To send a running job to the background: |
<Control>z bg |
| join |
Text Processing: Relational database operator |
|
|
Process Management: Terminates a process by its process identification number. |
kill pid |
| |
Remove suspended process #1 |
kill %1 |
| |
To use the strongest form of the kill command: |
kill -9 pid |
| less |
Shows file a page at a time. Like more, but you can use Page-Up too. Not on all systems |
less filename |
| Lex |
C Programming: Generate programs for lexical tasks |
|
| link |
File system: Call link function |
|
| Ln |
File system: Link files |
|
|
Make symbolic links; make a link file2, which points to file1 |
ln -s file1 file2 |
| locale |
Get locale-specific information |
|
| localedef |
Define locale environment |
|
| logger |
Shell programming: Log messages |
|
| login |
Logs in the system or starts a computer session |
|
| logname |
Return the user’s login name |
|
|
Ends your computer session; logs off the system |
|
| Lpr |
Text Processing: Show list of available printers and questions to direct your printing of a file to a particular printer |
lpr |
| |
If you put several filenames after lpr, this will typically send several files in a single print job. The -Pprinter option sends the job to the specified printer. If you do not specify a -Pprinter option, then lpr will use the contents of the PRINTER environment variable. You may wish to setup a default printer by putting a line like the following into your .login file: setenv PRINTER mylocalprinter |
lpr files
lpr -Pprinter files |
| lprm |
Remove print job 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. |
lprm -Pprinter job_numbers
|
| Lpq |
Show the queue of jobs for a given printer or default printer in case -Pprinter is not specified. e.g. to get the job number needed for removal, or to see how many other files will be printed before yours will come out |
lpq -Pprinter
|
| ls |
File system: Lists the files and subdirectories in your current directory. |
ls -Fltra |
| |
-l Lists long format
-t Lists by modification time
-r Lists in reverse order
-F Lists file type with special character
-a Lists all files including dot (.) files |
|
| lynx |
Starts a text-only web browser session at UW home page. It’s a textual World Wide Web browser |
lynx |
| |
Starts a Web browser session at a specific Web address. |
lynx url |
| mailx |
Process messages |
|
| make |
Maintain, update, and regenerate groups of programs; compiles source code |
|
|
Displays Unix Manual entry for a command. |
man command |
| |
To search Manual Index for a keyword or topic: |
man -k keyword |
| Mc |
“midnight commander” – Interactive file explorer. Provides an alternative to many typed commands. NB not installed on many systems |
|
| mesg |
Displays your talk and write message access status. |
mesg |
| |
To set your message status to yes or no: |
mesg y (or n) |
| mkdir |
File system: Creates a new directory within your current directory. |
mkdir directory |
| mkfifo |
File system: Make FIFO special file |
|
| more |
Text Processing: Displays a file one screen at a time. views a file, pausing every screenful. If no files are specified on the command line, then more displays standard input. For example, if you want to list a lot of files a screen at a time, type: ls | more
Press space to go forward one screen, enter to go forward one line. |
more file |
| |
Use <Spacebar> to scroll forward and q to quit. |
|
| Mv |
File system: Moves a file to a different directory. |
mv file directory
mv files directory |
| |
Moves a directory to a second directory. |
mv directory1 directory2 |
| |
To rename file1 as file2: |
mv file1 file2 |
| |
To rename directory1 as directory2: |
mv directory1 directory2 |
| |
To inquire before overwriting an existing file: |
mv -i file1 file2 |
| netscape |
Graphical web browser and Email Program: Mainly used for web browsing, it can also be used for sending and receiving email |
|
| newgrp |
Change to a new group |
|
| nice |
Process Management: Invoke a utility with an altered nice value to change priority of job |
|
| Nl |
Text Processing: Line numbering filter |
|
| Nm |
C Programming: Write the name list of an object file |
|
| nohup |
Process Management: Invoke a utility immune to hang-ups; it continue a job even after logout |
|
| Od |
Dump files in various formats |
|
| osview |
display the operating system statistics |
osview |
| paste |
Text Processing: Merge corresponding or subsequent lines of files |
|
|
Starts program to change account password. You’ll have to type your old password before you type a new one.
You won’t see the password when you type it, but you type it twice to make sure. Choose a password which can’t be easily guessed, and keep it secret. |
|
| patch |
Text Processing: Apply changes to files |
|
| pathchk |
File system: Check pathnames |
|
| pico |
Easy-to-use text editor: Starts the Pico text editor with a file,but not very powerful! The same as you get with the pine mailer. |
pico file |
| pine |
It’s an easy to use mail program. Starts the Pine® electronic mail program. |
|
| Pr |
Text Processing: Print files |
|
| printenv |
Show content of an environment variable. If variable is not typed, printenv will list all the environment variables. |
printenv [variable] |
| printf |
Shell programming: Write formatted output |
|
| Prs |
Print an SCCS file |
|
| Ps |
Process Management: Displays processes and their corresponding process identification numbers. |
|
| |
Display expanded list of all processes and typically show everybody’s processes. |
ps -ef |
| pushd |
Add entry to directory stack Use this to go temporarily to another directory. |
pushd directory |
| |
Type popd when you want to go back to the directory you were in when you typed pushd; means to remove entry from directory stack |
popd |
| pwd |
File system: Displays absolute pathname of current directory. i.e. show the directory that you are in (present working directory) |
|
| qalter |
Batch Utilities: Alter batch job |
|
| qdel |
Batch Utilities: Delete batch jobs |
|
| qhold |
Batch Utilities: Hold batch jobs |
|
| qmove |
Batch Utilities: Move batch jobs |
|
| qmsg |
Batch Utilities: Send message to batch jobs |
|
| qrerun |
Batch Utilities: Rerun batch jobs |
|
| qrls |
Batch Utilities: Release batch jobs |
|
| qselect |
Batch Utilities: Select batch jobs |
|
| qsig |
Batch Utilities: Signal batch jobs |
|
| qstat |
Batch Utilities: Show status of batch jobs |
|
| qsub |
Batch Utilities: Submit a script |
|
| quota |
Finding out your available disk space quota. Show how your disk usage compares with your permitted maximum. Your disk usage may exceed your “quota” for a short “grace period” (typically a week), but it may never exceed your “limit”. If the grace period runs out, you will have to delete files before you can create any more.
You may have to type “quota -v” to get full information. |
quota -v |
| Rcp |
Copy files between machines (insecurely). Usage is analogous to scp.
This method does not use encryption, so there is a risk of your password and other data being spied on. It should be avoided wherever scp is available |
rcp [username@]machine:file file |
| read |
Shell programming: Read a line from standard input |
|
| readonly |
Set the readonly attribute for variables |
|
| renice |
Process Management: Set nice values of running processes. Your command will have less impact on other users. number typically ranges from 0 to 19. process can either be a “PID” number as reported by ps or top, or “%jobnumber” as reported by jobs. |
renice number process |
| return |
Shell programming: Return from a function |
|
|
File system: Permanently deletes a file. |
rm file |
| |
To verify prior to removal |
rm -I file |
| |
To remove directory, subdirectories with files recursively |
rm -r directory |
| |
To forcibly remove directory content recursively without having write permission on it |
rm -rf directory |
| rmdir |
File system: Deletes an empty directory. |
rmdir directory |
| |
To verify prior to removal |
rmdir -i directory |
| Rz |
Recieve a file (to the unix system) using zmodem |
|
| scp |
Copy files between machines (securely) The syntax would copy a file from a remote machine to the local machine. To do the converse, use: scp file [username@]machine:file
Omit the “username@” bit if your username on the other machine is the same as on the local machine. |
scp [username@]machine:file file |
| sed |
Text Processing: Stream editor. It is most commonly used to perform search-and-replace operations on text. The following command globally replaces pattern with replacement. It also supports more complicated scripting – see the manual page |
sed 's/pattern/replacement/g' [file]
|
| set |
Set or unset options and positional parameters. The value of shell variables can be accessed as “$variable”. Shell variables are seen only by the shell, and are not passed to commands. |
set variable=value
|
| setenv |
List environmental variables. |
setenv |
|
Set an environment variable
The value of environment variables can be accessed as “$variable“. Block capitals are conventionally used for names of environment variables. Environment variables are passed from the shell to commands, and may affect the behavior of commands (e.g. $PRINTER affects lpr). |
setenv variable value |
| sftp |
Secure file transfer protocol |
|
| Sh |
Shell programming: Shell, the standard command language interpreter |
|
| shift |
Shell programming: Shift positional parameters |
|
| sleep |
Shell programming: Suspend execution for an interval |
|
| sort |
Text Processing: Sort, merge, or sequence check text files. Order the lines in a file or files alphabetically (this command does not alter the file or files — it merely displays the sorted output to the screen) |
sort files
|
| |
Displays contents of files sorted alphabetically in reverse order. |
sort -r files |
| |
Displays contents of files sorted numerically (puts 2 before 10 instead of after). |
sort -n files |
|
Checks the spelling in a file. |
spell file |
| split |
Split files into pieces |
|
| ssh |
Connect to another machine |
ssh hostname |
| staffdir |
Displays the Online UW Staff Directory. |
staffdir “lastname, firstname“ |
| |
To display all fields: |
staffdir -full “lastname, firstname“ |
| strings |
C Programming: Find printable strings in files |
|
| strip |
C Programming: Remove unnecessary information from executable files |
|
| stty |
Set the options for a terminal |
|
| Sz |
Send a file (to you) using zmodem |
|
| tabs |
Set terminal tabs |
|
| tail |
Text Processing: Copy the last ten lines of a file |
tail file |
|
Text Processing: To display the last n number of lines |
tail -n file |
|
Text Processing: It skips initial n number of lines and displays rest |
Tail +n file |
| talk |
Initiate a conversation with another user (end conversation with Control-C); talk works only between machines of the same architecture. This feature disabled on many systems. |
talk user[@machine] |
| Tar |
The tar command stands for “tape archive”. It is the “standard” way to read and write archives (collections of files and whole directory trees. It combines multiple files into one or vice-versa; store an image of dir.1 and it’s contents in file file.1 |
tar -cvf dir.1.tar dir.1 |
|
Extracts (x) files from the default tape drive while listing (v = verbose) the file names to the screen |
tar -xv dir.1.tar |
| tee |
Shell programming: Duplicate standard input |
|
| telnet |
Starts a telnet session with a remote computer. |
telnet host_address |
| test |
Shell programming: Evaluate expression |
|
| time |
Process Management: Time a simple command |
|
| times |
Process Management: Write process times |
|
| Tin, trn |
Read Usenet newsgroups |
|
| top |
Display the current, most computer-intensive commands. Press “q” to quit from the display |
top |
| touch |
File system: Change file access and modification times |
|
| tput |
Change terminal characteristics |
|
| Tr |
Text Processing: Translate characters |
|
| trap |
Process Management: Trap signals |
|
| tree |
Draw a tree-like recursive directory listing. Not installed on many systems |
|
| true |
Shell programming: Return true value |
|
| tsort |
Text Processing: Topological sort |
|
| Tty |
Return user’s terminal name |
|
| type |
Displays how a name would be interpreted if used as a command |
|
| ulimit |
Set or report file size limit |
|
| umask |
Get or set the file mode creation mask means change permissions on new files |
|
| unalias |
Remove alias definitions |
|
| uname |
Return system name |
|
| uncompress |
Expand compressed data |
|
| unexpand |
Text Processing: Convert spaces to tabs |
|
| unget |
Undo a previous get of an SCCS file |
|
| uniq |
Text Processing: Report or filter out repeated lines in a file |
|
| unix2dos |
adds CR’s to unix text files |
unix2dos <file> <new_file> |
| unlink |
File system: Call the unlink function |
|
| unset |
Unset values and attributes of variables and functions |
|
| uucp |
System-to-system copy |
|
| uudecode |
Decode a binary file |
|
| uuencode |
Encode a binary file |
|
| uustat |
uucp status inquiry and job control |
|
| uux |
Process Management: Remote command execution |
|
| val |
Validate SCCS files |
|
|
Text Processing: Starts the vi text editor with a file. |
vi file |
|
Displays a list of who is on system and what they are 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. |
|
| wait |
Process Management: Await process completion |
|
| Wc |
Text Processing: counts lines, words, and characters in file file. Variations:
wc -l counts lines in file file
wc -w counts words in file file
wc -c counts characters in file file |
wc -lwc file |
| what |
Identify SCCS files |
|
| where |
Find out the places where a command program is installed on the system. This uses your search path ($PATH) to know where to look. If the program is installed in more than one place, the first one listed is the one which is run when you type the command. |
where command |
| which |
List location of executable command. It’s same as where command, but only lists the first occurrence of the command. |
which command |
| who |
Display a list of users currently logged into system |
who |
|
Display list current user in that window |
whoami or who am i |
| write |
Write to another user’s terminal, (user) is a email address; <ctrl-c> to end |
write user |
| xargs |
Shell programming: Construct argument lists and invoke utility |
|
| xcal |
Graphical calculator application. Fairly intuitive to use. Type sums, or press the calculator buttons with the mouse |
|
| xemacs
|
Alternative version of emacs. The “normal” emacs is the GNU version. This is a slightly different version which you may or may not prefer. |
|
| xhost |
Permit another machine to open windows on the display. This command is insecure, because it makes no distinction between users on the remote machine. It should not be used when ssh is in use. |
xhost machine |
| xman |
Graphical interface to manual pages |
|
| yacc |
C Programming: Yet another compiler compiler |
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| zcat |
Text Processing: Expand and concatenate data |
zcat file |
| Zip |
zip the file |
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