Mounting file systems

In this part of the lesson about file systems we'll learn how to use the commands mount and umount

We've mentioned previously that there's a different idea in Linux as to what constitutes a floppy disk drive, a CD-ROM drive and another partition of your hard disk (the Windows partition, for example). Though some windows managers for Linux have provisions for clicking on an icon to access a floppy drive, for example, the method behind this is quite different from other OSes. In Linux the floppy drive or other device must be "mounted". That means basically, incorporating it temporarily into your Linux file system or, in other words, telling Linux that it is a file to be written to or copied from.

To access a floppy disk from the command line of our shell, we would use the command mount and type the following: (remember: you need to be working as 'root' to do this)

mount -t ext2 /dev/fd0 /floppy

Now this assumes a couple of things:

• you have a floppy disk in the drive (you'd be surprised how many times I forget to actually put the floppy in the drive)
• in this example, the floppy type (indicated by the option -t) is a Linux formatted floppy. If you want to mount a Windows floppy, change the option to -t vfat
• in your root directory (you can get to it by typing: cd /), you have a directory called floppy. If you don't, you should create it (mkdir floppy). Some Linux distributions create this automatically during the installation process. Some don't.

Let's explain what we've just done here. When we typed: mount -t ext2 /dev/fd0 /floppy we told Linux that our floppy disk is now part of our Linux file system (/dev/fd0) and that any files we would like to store on that disk will be copied to /floppy, as if it were just another directory on our Linux system. If you did it right, typing the command 'df' (the command to see how much free disk space) should include something like this:

/dev/fd0

1390

649

669

49%

/floppy

Your numbers may vary (especially if your floppy is blank!)

Now, to copy to and from the floppy disk, you would type:

cp my_file /floppy

If you wanted to create individual subdirectories on the floppy, you would first change to the /floppy directory:

cd /floppy

Then you would use the mkdir command to create the directories you want. You can also use the command cp -r my_directory/ /floppy to copy the directory automatically to the floppy. (make sure you have space! - I have on occasion tried to copy a 3MB file to a 1MB floppy!)

Mounting other devices

You can also use the mount command to copy to and from other devices.

If you would like to get some files from a CD-ROM, the standard command to do this is:

mount -t iso9660 /dev/hdb /cdrom

The type, iso9660 is the standard file system for a CD. The device (/dev/hdb) is the non-SCSI type of CD-ROM and the mount point (/cdrom) should exist. If it doesn't, you should create it in the root directory with 'mkdir', just as you may have done with the /floppy directory.

Remember that the concept of CD-ROM is read only. You won't be able to write to this type of CD-ROM drive. A message will tell you that when you mount this type of device.

Mounting another partition of the hard disk.

Many people may have preferred to install Linux along with another operating system. You may have Linux and Windows installed in the same computer. If you would like to access files on the Windows partition you would type the following command:

mount -t vfat /dev/hda1 /mnt

Windows is always in the primary partition, so that's why we've used the device /hda1 (hard disk partition 1). The choice for /mnt is the standard mount point in this case. You may use the /mnt directory to mount the other devices (floppies, CDs) as well. I use the different empty directories (/floppy /cdrom /mnt) to avoid confusion.

If you change to the mount directory (cd /mnt) and then type: ls and you'll see something interesting. The directories are blue but the files are green (or red - depending on your distribution of Linux). You won't have the various color combinations as you do in Linux. That's because Windows' file system doesn't distinguish file types. Everything looks like it's a program (binary) instead of a regular file.

When you copy files from the Windows partition to the Linux partition you should bear this in mind. For example, if you wanted to copy an mp3 file from the Windows partition to the Linux partition to test out your sound configuration, it would show up as a executable program and not just a standard file under Linux. This doesn't effect your playing it, but for a more accurate accounting of what you have on your system, you may want to change the permissions of the file so that it shows up as a regular file in your color scheme. We'll talk about file permissions and and making changes to them shortly.

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