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<h1 class="SECT1"><a id="FILESYSTEM-STRUCTURE-MOUNTING"
name="FILESYSTEM-STRUCTURE-MOUNTING">9.4 Mounting Devices</a></h1>
<p>As was previously discussed in <a
href="system-configuration.html#SYSTEM-CONFIGURATION-LAYOUT">Section 4.1.1</a>, all the
drives and devices in your computer are one big filesystem. Various hard drive
partitions, CD-ROMs, and floppies are all placed in the same tree. In order to attach
these drives to the filesystem so that you can access them, you have to use the <tt
class="COMMAND">mount</tt>(1) and <tt class="COMMAND">umount</tt>(1) commands.</p>
<p>Some devices are automatically mounted when you boot up your computer. These are
listed in the <tt class="FILENAME">/etc/fstab</tt> file. Anything that you want to be
mounted automatically gets an entry in that file. For other devices, you'll have to issue
a command every time you want to use the device.</p>
<div class="SECT2">
<h2 class="SECT2"><a id="AEN3319" name="AEN3319">9.4.1 <tt
class="FILENAME">fstab</tt></a></h2>
<p>Let's look at an example of the <tt class="FILENAME">/etc/fstab</tt> file:</p>
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<samp class="PROMPT">%</samp> <kbd class="USERINPUT">cat /etc/fstab</kbd>
/dev/sda1 / ext2 defaults 1 1
/dev/sda2 /usr/local ext2 defaults 1 1
/dev/sda4 /home ext2 defaults 1 1
/dev/sdb1 swap swap defaults 0 0
/dev/sdb3 /export ext2 defaults 1 1
none /dev/pts devpts gid=5,mode=620 0 0
none /proc proc defaults 0 0
/dev/fd0 /mnt ext2 defaults 0 0
/dev/cdrom /mnt/cdrom iso9660 ro 0 0
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<p>The first column is the device name. In this case, the devices are five partitions
spread out across two SCSI hard drives, two special filesystems that don't need a device,
a floppy, and a CD-ROM drive. The second column is where the device will be mounted. This
needs to be a directory name, except in the case of a swap partition. The third column is
the filesystem type of the device. For normal Linux filesystems, this will be <var
class="LITERAL">ext2</var> (second extended filesystem). CD-ROM drives are <var
class="LITERAL">iso9660</var>, and Windows-based devices will either be <var
class="LITERAL">msdos</var> or <var class="LITERAL">vfat</var>.</p>
<p>The fourth column is a listing of options that apply to the mounted filesystem.
defaults is fine for just about everything. However, read-only devices should be given
the <var class="LITERAL">ro</var> flag. There are a lot of options that can be used.
Check the <tt class="FILENAME">fstab</tt>(5) man page for more information. The last two
columns are used by <tt class="COMMAND">fsck</tt> and other commands that need to
manipulate the devices. Check the man page for that information as well.</p>
<p>When you install Slackware Linux, the setup program will build much of the <tt
class="FILENAME">fstab</tt> file.</p>
</div>
<div class="SECT2">
<h2 class="SECT2"><a id="AEN3340" name="AEN3340">9.4.2 <tt class="COMMAND">mount</tt> and
<tt class="COMMAND">umount</tt></a></h2>
<p>Attaching another device to your filesystem is easy. All you have to do is use the <tt
class="COMMAND">mount</tt> command, along with a few options. Using <tt
class="COMMAND">mount</tt> can simplified if the device has an entry in the <tt
class="FILENAME">/etc/fstab</tt> file. For example, let's say that I wanted to mount my
CD-ROM drive and that my <tt class="COMMAND">fstab</tt> file looked like the example from
the previous section. I would call <tt class="COMMAND">mount</tt> like so:</p>
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<samp class="PROMPT">%</samp> <kbd class="USERINPUT">mount /cdrom</kbd>
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<p>Since there is an entry in <tt class="FILENAME">fstab</tt> for that mount point, <tt
class="COMMAND">mount</tt> knows what options to use. If there wasn't an entry for that
device, I would have to use several options for <tt class="COMMAND">mount</tt>:</p>
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<samp class="PROMPT">%</samp> <kbd
class="USERINPUT">mount -t iso9660 -o ro /dev/cdrom /cdrom</kbd>
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<p>That command line includes the same information as the example <tt
class="FILENAME">fstab</tt> did, but we'll go over all the parts anyways. The <var
class="OPTION">-t iso9660</var> is the filesystem type of the device to mount. In this
case, it would be the iso9660 filesystem which is what CD-ROM drives most commonly use.
The <var class="OPTION">-o ro</var> tells mount to mount the device read-only. The <tt
class="FILENAME">/dev/cdrom</tt> is the name of the device to mount, and <tt
class="FILENAME">/cdrom</tt> is the location on the filesystem to mount the drive.</p>
<p>Before you can remove a floppy, CD-ROM, or other removable device that is currently
mounted, you'll have to unmount it. That is done using the <tt
class="COMMAND">umount</tt> command. Don't ask where the “n” went because we
couldn't tell you. You can use either the mounted device or the mount point as the
argument to <tt class="COMMAND">umount</tt>. For example, if you wanted to unmount the
CD-ROM from the previous example, either of these commands would work:</p>
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<samp class="PROMPT">#</samp> <kbd class="USERINPUT">umount /dev/cdrom</kbd>
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">umount /cdrom</kbd>
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