Translations by Jen Ockwell

ubuntu-doc@lists.ubuntu.com (Ubuntu Documentation Project)

2006-09-07

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Credits and License

This document is made available under the Creative Commons ShareAlike 2.5 License (CC-BY-SA).

Ubuntu Documentation Project

Canonical Ltd. and members of the <placeholder-1/>

The Ubuntu Documentation Project

Using this Guide

This guide 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, file names or paths to directories will be shown using a <command>monospace font</command>.

All the commands on this guide are to be issued from a command prompt in a <application>Terminal</application> and will be shown as: <screen>command to type</screen>

To open a <application>Terminal</application> choose <menuchoice><guimenu>Applications</guimenu><guimenuitem>Accessories</guimenuitem><guimenuitem>Terminal</guimenuitem></menuchoice>.

File and Directory Commands

cd

To navigate into the root directory, type: <screen>cd /</screen>

To navigate to your home directory, type: <screen>cd</screen> or <screen>cd ~</screen>

To navigate up one directory level, type: <screen>cd ..</screen>

To navigate to the previous directory (or back), type: <screen>cd -</screen>

To navigate through multiple levels of directories at once, specify the full directory path that you want to go to. For example, type: <screen>cd /var/www</screen> to go directly to the <filename class="directory">/www</filename> subdirectory of <filename class="directory">/var/</filename>. As another example, type: <screen>cd ~/Desktop</screen> to move you to the <filename class="directory">Desktop</filename> subdirectory inside your home directory.

pwd

ls

cp

mv

rm

By default, <command>rm</command> will not remove directories. To remove a directory, you must use the <command>-R</command> option. For example, <screen>rm -R foobar</screen> will remove the directory foobar, <emphasis role="strong">and all of its contents!</emphasis>

mkdir

df

The <command>df</command> command displays filesystem disk space usage for all partitions. <screen>df -h</screen> will give information using megabytes (M) and gigabytes (G) instead of blocks (<emphasis role="strong">-h</emphasis> means "human-readable").

free

The <command>free</command> command displays the amount of free and used memory in the system. <screen>free -m</screen> will give the information using megabytes, which is probably most useful for current computers.

top

The <command>top</command> command displays information on your GNU/Linux system, running processes and system resources, including CPU, RAM &amp; swap usage and total number of tasks being run. To exit <application>top</application>, press <keycap>q</keycap>.

uname

The <command>uname</command> command with the <emphasis role="strong">-a</emphasis> option, prints all system information, including machine name, kernel name &amp; version, and a few other details. Most useful for checking which kernel you're using.

lsb_release

The <command>lsb_release</command> command with the <emphasis role="strong">-a</emphasis> option prints version information for the Linux release you're running. For example, typing: <screen>lsb_release -a</screen> will give you: <screen> No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 10.04 LTS Release: 10.04 LTS Codename: lucid</screen>

Executing Commands with Elevated Privileges

The following commands will need to be prefaced with the <command>sudo</command> command. Please see <ulink url="https://help.ubuntu.com/community/RootSudo">RootSudo</ulink> for information on using <command>sudo</command>.

Adding a New Group

The <command>addgroup</command> command is used to create a new group on the system. To create a new group, type: <screen>addgroup newgroup</screen> The above command will create a new group called <emphasis role="strong">newgroup</emphasis>.

The <command>adduser</command> is used to create new users on the system. To create a new user, type: <screen>adduser newuser</screen> The above command will create a new user called <emphasis role="strong">newuser</emphasis>.

To assign a password for the new user use the <command>passwd</command> command: <screen>passwd newuser</screen>

Finally, to assign the new user to the new group, type: <screen>adduser newuser newgroup</screen>

The default behavior for a command may usually be modified by adding a <emphasis role="strong">-- <emphasis>option</emphasis></emphasis> to the command. The <link linkend="ls"><command>ls</command></link> command, for example, has a <emphasis role="strong">-s</emphasis> option so that <command>ls -s</command> will include file sizes in the listing. There is also a <emphasis role="strong">-h</emphasis> option to get those sizes in a "human readable" format.

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

<emphasis role="strong"><emphasis>command</emphasis> --help</emphasis> and <emphasis role="strong">man <emphasis>command</emphasis></emphasis> are the two most important tools at the command line.

Virtually all commands understand the <emphasis role="strong">-h</emphasis> (or <emphasis role="strong">--help</emphasis>) option which will produce a short usage description of the command and it's options, then exit back to the command prompt. Type <screen>man -h</screen> or <screen>man --help</screen> 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 <command>man command</command> to bring up a longer manual entry for the specified command. For example, <screen>man mv</screen> will bring up the <command>mv</command> (move) manual.

Move up and down the man file with the arrow keys, and quit back to the command prompt with <keycap>q</keycap>.