ITS Documentation

Frequently Used Unix Commands

R1159 • May 2009

The Unix operating system supports many commands. To review a more complete definition of any of the commands listed below, type man command at the Unix shell prompt (%), where you have replaced command with the name of a Unix command. For example, type man exit to find out more about the exit command.

NOTE: This document assumes you are using Unix on the ITS Login Service (host name login.itd.umich.edu). These instructions apply to many other Unix machines; however, you may notice different behavior if you are not using the ITS Login Service.

TIP: The variable files refers to a list of any number of files separated by white space; in the same way; names refers to a list of file or directory names separated by white space.

Table of Contents


General

apropos command
Locate commands by keyword lookup.
exit
Terminate your current session, or shell.
man command
Display the Unix manual page describing a given Unix command.

File System Navigation

cd
Return to your home directory.
cd directory
Change directory to make directory your current directory.
file files
Determine file type.
ls
List the contents of the current directory.
ls names
List the contents of the directories; names can name files and/or directories:
ls -l
. . . in a long format, showing permissions, owner, size, and other file info.
ls -a
. . . all files, including "hidden" files (file names that begin with a dot ".").
ls -R
. . . Recursively, for all subdirectories.
ls -t
. . . in time order (when modified, newest to oldest) rather than in name order.
pwd
Display the name of the current directory, or "print working directory."

File/Directory Manipulation

compress files
Reduces the size of a file.
uncompress files
Restores compressed files to their original form.
cp file1 file2
Copy file(s).
cp files directory
Copy file(s) into a directory.
cp -r dir1 dir2
Copy a directory and, recursively, its subdirectories.
mkdir directory
Create, or "make" a directory.
mv file1 file2
Move a file or, if file1 and file2 are in the same directory, rename a file.
mv files directory
Move files into a directory.
mv dir1 dir2
If directory dir2 exists, move dir1 into dir2; otherwise, rename dir1 as dir2.
rm files
Remove (erase) file(s).
rm -r names
Remove files, directories, and recursively, any subdirectories.
rmdir directory
Remove directory (directory must be empty).

Data Manipulation

cat files
Concatenate file(s); you can use cat to display the contents of a file (this is not advisable if the file is a binary file).
grep "pattern" files
Display all lines in the files that match a pattern.
more files
Display contents of files one screen at a time.
sort 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 -r files
. . . in reverse order.
sort -n files
. . . numerically (puts 2 before 10 instead of after).

Networking/Communications

ssh hostname
Connect to a remote host using Secure Shell.

Miscellaneous

!!
Repeat last shell command.
!string
Repeat last shell command that began with string (for example, type "!m" to repeat the last command that began with "m").
cal
Display a calendar of the current month.
cal month year
Display a calendar of the given month and year. Note that the year must be fully qualified, for example, "2003" and not "03."
clear
Clears terminal screen.
date
Display the current local date and time.
who
Display a list of users currently logged in.

Additional Resources

Visit ITS's Information System to obtain ITS computer documentation and other resources. A list of relevant documents follows:

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For further help with this or any other topic, call 734-764-HELP [4357] or submit an online service request.