Translations by Carda

The <command>~</command> character represents the current user's home directory. As seen above, <command>cd ~</command> is equivalent to <command>cd /home/username/</command>. However, when running a command as root (using <command>sudo</command>, for example), <command>~</command> points instead to <filename class="directory">/root</filename>. When running a command with <command>sudo</command>, the full path to your home directory must be given.

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.

<application>GNOME Terminal</application> also displays this information in the title bar of its window.

Used with the <command>-l</command> options, <command>ls</command> outputs various other information alongside the filename, such as the current permissions on the file, and the file's owner.

The <command>cp</command> command makes a copy of a file. For example, type: <screen>cp foo bar</screen> to make an exact copy of <filename>foo</filename> and name it <filename>bar</filename>. <filename>foo</filename> will be unchanged.

The <command>mv</command> command moves a file to a different location or will rename a file. Examples are as follows: <screen>mv foo bar</screen> will rename the file <filename>foo</filename> to <filename>bar</filename>. <screen>mv foo ~/Desktop</screen> will move the file <filename>foo</filename> to your <filename class="directory">Desktop</filename> directory but will not rename it.

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>

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").

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.

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>.

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.

The <command>ifconfig</command> command reports on your system's network interfaces.

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>.

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>.

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.

<screen>man man</screen> will bring up the manual entry for the <command>man</command> command, which is a good place to start.

<screen>man intro</screen> 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 <command>info</command> pages, which are generally more in-depth than <command>man</command> pages. Try <screen>info info</screen> for the introduction to info pages.

This is the same as the <command>apropos</command> command.

<command>man -k foo</command>, will search the man files for <emphasis>foo</emphasis>. Try <screen>man -k nautilus</screen> to see how this works. <placeholder-1/>

This is the same as the <command>whatis</command> command.

<command>man -f foo</command>, searches only the titles of your system's man files. For example, try <screen>man -f gnome</screen><placeholder-1/>

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 <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo> won't paste in with <keycombo><keycap>Ctrl</keycap><keycap>V</keycap></keycombo>. 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 <menuchoice><guimenuitem>Paste</guimenuitem></menuchoice> from the menu.