BasicCommands - Community Ubuntu Documentation

"Under Linux there are GUIs (graphical user interfaces), where you can point and click and drag, and hopefully get work done without first reading lots of documentation. The traditional Unix environment is a CLI (command line interface), where you type commands to tell the computer what to do. That is faster and more powerful, but requires finding out what the commands are." -- from man intro(1)

Using this page

This page will make you familiar with basic GNU/Linux shell commands.
It is not intended to be a complete guide to the command line, just an introduction to complement Ubuntu's graphical tools.
All command names will be in bold.
Commands needing to be typed will be in "bold with quotes".
All of the commands on this page are to be issued from a command prompt in a terminal.
Note that Linux is case sensitive. User, user, and USER are all different to Linux.

Starting a Terminal

In Gnome (Ubuntu)

The terminal can be found at Applications menu --> Accessories --> Terminal.

In Xfce (Xubuntu)

The terminal can be found at Applications menu --> System --> Terminal.

Commands

sudo: Executing Commands with Elevated Privileges

Most of the following commands will need to be prefaced with the sudo command if you will be working with directories or files not owned by your account. Please see RootSudo for information on using sudo.

File & Directory Commands

pwd: The pwd command will allow you to know in which directory you're located (pwd stands for "print working directory"). Example: "pwd" in the Desktop directory will show "~/Desktop". Note that the Gnome Terminal also displays this information in the title bar of it's window - see the example screenshot at the top of this page.
ls: The ls command will show you the files in your current directory. Used with certain options, you can see sizes of files, when files where made, and permissions of files. Example: "ls ~" will show you the files that are in your home directory.
- cd: The cd command will allow you to change directories. When you open a terminal you will be in your home directory. To move around the file system you will use cd. Examples:
  - To navigate into the root directory, use "cd /"
  - To navigate to your home directory, use "cd" or "cd ~"
  - To navigate up one directory level, use "cd .."
  - To navigate to the previous directory (or back), use "cd -"
  - To navigate through multiple levels of directory at once, specify the full directory path that you want to go to. For example, use, "cd /var/www" to go directly to the /www subdirectory of /var/. As another example, "cd ~/Desktop" will move you to the Desktop subdirectory inside your home directory.
cp: The cp command will make a copy of a file for you. Example: "cp file foo" will make a exact copy of "file" and name it "foo", but the file "file" will still be there. When you use mv that file would no longer exist, but when you use cp the original file stays and a new copy is made.
mv: The mv command will move a file to a different location or will rename a file. Examples are as follows: "mv file foo" will rename the file "file" to "foo". "mv foo ~/Desktop" will move the file "foo" to your Desktop directory but will not rename it. You must specify a new file name to rename a file.
- To save on typing, you can substitute '~' in place of the home directory.
- Note that if you are using mv with sudo you will not be able to use the ~ shortcut, but will have to use the full pathnames to your files. This is because when you are working as root, ~ will refer to the root account's home directory, not your own.
rm : Use this command to remove or delete a file in your directory. It will not work on directories which have files in them (use rmdir instead).
mkdir: The mkdir command will allow you to create directories. Example: "mkdir music" will create a music directory.
man: The man command is used to show you the manual of other commands. Try "man man" to get the man page for man itself. See the "Man & Getting Help" section down the page for more information.

System Information Commands

df: The df command displays filesystem disk space usage for all partitions. "df -h" is probably the most useful - it uses megabytes (M) and gigabytes (G) instead of blocks to report. (-h means "human-readable")
free: The free command displays the amount of free and used memory in the system. "free -m" will give the information using megabytes, which is probably most useful for current computers.
top: The top command displays information on your Linux system, running processes and system resources, including CPU, RAM & swap usage and total number of tasks being run. To exit top, press "q".
uname -a: The uname command with the -a option prints all system information, including machine name, kernel name & version, and a few other details. Most useful for checking which kernel you're using.
lsb_release -a: The lsb_release command with the -a option prints version information for the Linux release you're running, for example:

user@computer:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 6.06 LTS
Release:        6.06
Codename:       dapper

ifconfig reports on your system's network interfaces.

Adding A New User

"adduser newuser" command will create a new general user called "newuser" on your system, and to assign a password for the newuser account use "passwd newuser".

Options

The default behavior for a command may usually be modified by adding a --option to the command. The ls command for example has an -s option so that "ls -s" will include file sizes in the listing. There is also a -h option to get those sizes in a "human readable" format.

Options can be grouped in clusters so "ls -sh" is exactly the same command as "ls -s -h". Most options have a long version, prefixed with two dashes instead of one, so even "ls --size --human-readable" is the same command.

"Man" and getting help

$/!\$ command --help and man command are the two most important tools at the command line.

Virtually all commands understand the -h (or --help) option which will produce a short usage description of the command and it's options, then exit back to the command prompt. Try "man -h" or "man --help" to see this in action.

Every command and nearly every application in Linux will have a man (manual) file, so finding them is as simple as typing "man "command"" to bring up a longer manual entry for the specified command. For example, "man mv" will bring up the mv (Move) manual.

Move up and down the man file with the arrow keys, and quit back to the command prompt with "q".

"man man" will bring up the manual entry for the man command, which is a good place to start!

"man intro" is especially useful - it displays the "Introduction to user commands" which is a well-written, fairly brief introduction to the Linux command line.

There are also info pages, which are generally more in-depth than man pages. Try "info info" for the introduction to info pages.

Searching for man files

If you aren't sure which command or application you need to use, you can try searching the man files.

man -k foo will search the man files for foo. Try "man -k nautilus" to see how this works.
- Note that this is the same as the apropos command.
man -f foo searches only the titles of your system's man files. Try "man -f gnome", for example.
- This is the same as the whatis command.

Other Useful Things

Pasting in commands

Often, you will be referred to instructions that require commands to be pasted into the terminal. You might be wondering why the text you've copied from a web page using ctrl+C won't paste in with ctrl+V. Surely you don't have to type in all those nasty commands and filenames? Relax. Middle Button Click on your mouse (both buttons simultaneously on a two-button mouse) or Right Click and select Paste from the menu.

Save on typing

Up Arrow or ctrl+p	Scrolls through the commands you've entered previously.
Down Arrow or ctrl+n	Takes you back to a more recent command.
Enter	When you have the command you want.
tab	A very useful feature. It autocompletes any commands or filenames, if there's only one option, or else gives you a list of options.

Change the text

The mouse won't work. Use the Left/Right arrow keys to move around the line. (is this correct? I'll check at home).

When the cursor is where you want it in the line, typing inserts text - ie it doesn't overtype what's already there.

ctrl+a or Home	Moves the cursor to the start of a line.
ctrl+e or End	Moves the cursor to the end of a line.
ctrl+b	Moves to the beginning of the previous or current word.
ctrl+k	Deletes from the current cursor position to the end of the line.
ctrl+u	Deletes the whole of the current line.
ctrl+w	Deletes the word before the cursor.

More Information

AptGetHowto - using apt-get to install packages from the command line.
Commandline Repository Editing - adding the Universe/Multiverse repositories through the command line.
grep Howto - grep is a powerful command line search tool.
find Howto - locate files on the command line.
CommandlineHowto - longer and more complete than this basic guide, but still unfinished.
HowToReadline - information on some more advanced customization for the command line.

For more detailed tutorials on the Linux command line, please see:

http://linuxcommand.org/ - basic BASH tutorials, including BASH scripting
http://linuxsurvival.com/index.php - Java-based tutorials
http://rute.2038bug.com/index.html.gz - a massive online book about system administration, almost all from the command line.

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