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
- apropos command
- Locate commands by keyword lookup.
- Terminate your current session, or shell.
- man command
- Display the Unix manual page describing a given Unix command.
File System Navigation
- Return to your home directory.
- cd directory
- Change directory to make directory your current directory.
- file files
- Determine file type.
- 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.
- Display the name of the current directory, or "print working directory."
- 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).
- 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).
- ssh hostname
- Connect to a remote host using Secure Shell.
- Repeat last shell command.
- Repeat last shell command that began with string (for
example, type "!m" to repeat the last command that began with "m").
- 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."
- Clears terminal screen.
- Display the current local date and time.
- Display a list of users currently logged in.
Visit ITS's Information System to obtain ITS computer documentation and other resources. A list of relevant documents follows:
The ITS Service Center provides a variety of computing help resources.
For further help with this or any other topic, call 734-764-HELP  or submit an online service request.