mount your files the Linux way

In Linux, if you want to access a filesystem be it a CDROM, a partition or a different drive including zip, floppy, usb keys and so on, you have to mount the filesystem first prior to start using it. In most cases, the system will do it for you. But sometimes you have to do it yourselves. This you do by using the 'mount' command. Here I will explain different things you can achieve by using this very important and useful command.

Check which filesystems are mounted
Just enter the command:

$ mount

...to see all the filesystems that are mounted on your machine.

Re-mount a drive as read-only

This is useful if you want to take a backup of a filesystem in a production server. Once you have taken the backup, you can remount the filesystem as read-write. For example, if I want to remount the already mounted partition /dev/hda2 as read-only, I enter the following mount command:

# mount -o remount,ro /dev/hda2 /mnt/C/

... so that no one can write to the partition while the backup is going on. Once the backup is finished, I can remount it again as read-write:

# mount -o remount,rw /dev/hda2 /mnt/C/

ro - ReadOnly
rw - ReadWrite

You will find the above command useful in a situation in which your system gets corrupt. And when you boot into single user mode, the filesystem is mounted read-only. In which case, you have to remount it as read-write (see the above command) inorder to make changes to the configuration files.

Mounting a ISO image file to view its contents

If you have downloaded an ISO image (perhaps a Linux distribution) from the net and you want to see the contents of the file, there is an easy way of achieving it in Linux. You just mount it using the loopback device as follows:

# mount -t iso9660 -o loop,ro  knoppix-4.0.iso /mnt/iso

This is desirable in a situation where, you have downloaded a Linux ISO on to your harddisk. But your computer's BIOS does not support booting from the CD Drive. In which case, you have to create a boot disk (floppy) so that you can start the installation by booting from the floppy. Most Linux ISO's contain a floppy bootdisk image which you can copy to your floppy.

Move a already mounted filesystem to another location

I have already mounted a FAT32 partition in the '/mnt/D/' location. Now if I want to delink it from the current location and make it available at another location, I use the --move flag with the mount command as follows:

# mount --move /mnt/D/ /mnt/newLocation/

Now all the files on my FAT32 partition have been moved from /mnt/D/ to the /mnt/newlocation/. The files have not been actually moved but has been decoupled from /mnt/D/ mount point and linked at /mnt/newLocation/ .

Mount a filesystem simultaneously at two different places

I can use the --bind or --rbind option to mount an already mounted, part of file hierarchy or an entire filesystem to another location with different rights.

For example, I have a subdirectory called 'softwares' in the read-only mount point /mnt/D/ , which I want to make accessible to other users for writing data. I can achieve this by using the --bind command as follows:

# mount -o rw --bind /mnt/D/softwares /mnt/backup

Now only the subdirectory 'softwares/' is accessible as read-write in the location /mnt/backup .

If you ask me, mount is a very important command in the Linux toolbox. Because, if there was no mount, Linux would not have been the same OS that it is now. The mount command has lots of other options. You may read the man page of mount to know more about it.