UNIX Shell Commands

UNIX shell commands are vital for webmasters to manipulate files via SSH and Mac and Linux geeks who want to really master their systems.

Basic UNIX Shell Commands

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 ITCS 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 ITCS 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.

NOTE: This document is also available in these formats:

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Table of Contents

• General

   

• File System Navigation

   

• File/Directory Manipulation

   

• Data Manipulation

   

• Networking/Communications

   

• Miscellaneous

   

• Additional Resources

   

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

finger user@umich.edu

Displays information about a U-M user from the U-M Online Directory.

 

ssh hostname

Connect to a remote host using Secure Shell.

 

telnet hostname

Connect to a remote host using the telnet protocol.

 

talk user

Initiate a conversation with another user (end conversation with Control-C); talk works only between machines of the same architecture.

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.

Tutorials

If you http://www.itd.umich.edu/itcsdocs/r1159/

http://linux-newbie.sunsite.dk/