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Quick Reference: Unix Commands

Commonly used commands and options on Unix computers.

  The following format is used for commands:
      Italic indicates a variable that you supply
      Bold indicates exactly what you type
  To display a command description from the Unix Manual:
      man command
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Command Action Example
alias Creates a temporary name for a Unix command. alias   name command
  To remove an alias: unalias   name
ansiprint Prints a file to a printer connected to your computer. ansiprint   file
assets Displays your account resources, use, and threshold.      
bg Places a suspended job in the background.      
cat Displays a specified file. cat   file
cd 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
  
chmod Changes permission status for a file or directory. chmod   code file
chmod   code directory
  To keep a file private: chmod   600 file
  To give everyone read permission: chmod   664 file
compress Reduces the size of a file and adds .Z to the file's name. compress   file
  To restore a compressed file: uncompress   file.Z
cp 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
diff Compares two files and displays the differences.      
fg Restarts a suspended job in the foreground.      
finger Displays user information at the specified computer. finger   userid@computer
  To change your finger entry information: chfn
ftp Starts the file transfer program with a remote computer. ftp   address
grep Finds lines in a file matching a character pattern. 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
  
head 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: !   n
  To repeat your most recent command: !!
jobs 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
kill Terminates a process by its process identification number. kill   pid
  To use the strongest form of the kill command: kill -9   pid
logout Ends your computer session.  
ls 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 lynx
  Starts a Web browser session at a specific Web address. lynx   url
man Displays Unix Manual entry for a command. man   command
  To search Manual Index for a keyword or topic: man -k   keyword
mesg Displays your talk and write message access status. mesg
  To set your message status to yes or no: mesg y (or n)
mkdir Creates a new directory within your current directory. mkdir   directory
more Displays a file one screen at a time. more   file
  Use <Spacebar> to scroll forward and q to quit.  
mv Moves a file to a different directory. mv   file 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
passwd Starts program to change account password.  
pico Starts the Pico text editor with a file. pico   file
pine Starts the Pine® electronic mail program.  
ps Displays processes and their corresponding process identification numbers.  
pwd Displays absolute pathname of current directory.  
rm Permanently deletes a file. rm   file
  To verify prior to removal: rm -i   file
rmdir Deletes an empty directory. rmdir   directory
  To verify prior to removal: rmdir -i   directory
spell Checks the spelling in a file. spell   file
telnet Starts a telnet session with a remote computer. telnet   address
vi Starts the vi text editor with a file. vi   file
w Displays a list of who is on system.  
wc Counts lines, words, and characters in a file. wc   file

Special commands and characters:

Redirection

    <     Routes input to command from file
    >     Routes output from command to file
    >>   Appends output to existing file
    |     Routes output between commands

Wildcards used in filenames

    *     Matches any number of characters
    ?     Matches one character

Control codes

    <Control>s     Suspends the screen display
    <Control>q     Restarts suspended display
    <Control>d     Signals end of file
    <Control>c     Cancels a command
    <Control>z     Suspends a process or job:
use fg to restart
    <Control>u     Clears the command line