Adding/Removing a Filesystem
You can permemently add or remove filesystems from your system by adding or removing a line from fstab. This operation requires root to do this, as it effects all users.
When adding a file system to fstab, first add in the line in the same format as shown in the file (and described below). Then you can mount it using mount /mountpoint. If all goes well, the filesystem will mount.
To permemently remove a filesystem, delete the line that you don't want anymore. Remember to unmount the filesystem first, by umount /mountpoint.
Sample fstab
Below the fstab file from my machine:
/dev/hda5 / ext2 defaults 1 1 none /proc proc defaults 0 0 /dev/hda7 /mnt hfs user,umask=0000,rw 0 0 /dev/fd0 /floppy auto noauto,user,umask=7055 0 0 /dev/hda6 swap swap defaults 0 0 /dev/hdc /cdrom auto noauto,ro,user 0 0 /dev/scd0 /cdrw auto noauto,ro,user 0 0 /dev/sda /mp3 ext2 defaults 1 1
Understanding the Columns
Device Location
The first column represents the device you will be mounting. For everything, except /proc, this device will be in /dev/ somewhere.
Note: Linux expects /proc to have a device called none. /proc is a "virtual" filesystem created by the kernel to show users what's going on inside of the kernel. Some programs use it to figure out cpuload, memory usage, etc.
Mount Point
The second column represents the mount point -- the virtual place where you want the disk to appear. For example, I have setup /dev/scd0 to appear at /cdrw. Now when I mount /cdrw whatever filesystem that is on the SCSI CD 0 (/dev/scd0) device will appear in /cdrw.
Note: The root filesystem (your primary Linux partition), must always be mounted on /. /proc must always be mounted on /proc.
Filesystem Type
The third column tells Linux the type of filesystem it is mounting. Common ones include:
- auto - Automagically detect filesystem. This is most useful on mount points where the filesystem type frequently changes, like most removable media.
- ext - The Linux Filesystem
- proc - /proc filesystem, displays system information
- iso9660 - Commonly used on CD-ROMs, supported by almost all OS's the support CD-ROMs. This is the default filesystem for external media in Linux.
- hfs - HFS Standard format, often used in Mac OS for smaller disks.
- hfsplus - HFS Plus format, often used in Mac OS for larger disks. Requires a special patch to work, and is unreliable at this time.
- fat - Microsoft Windows Disk Format, supporting 256 character long filesystem.
- msdos - Old MS-DOS disks
- ... and more such as: minix, ext, ext2, xiafs, iso9660, romfs ,ufs, ntfs, qnx4, bfs
Special Options
For ext2, swap or proc disks, you will most likely just need to put in defaults.
For HFS, MSDOS and FAT disks don't support permissions, so you must tell Linux what do with them. The user option allows users to mount these disks. rw allows the filesystem to be read or written from. umask=0100 sets the permissions for the disk (owner read,write, everybody else nothing). If you want to exec Linux binaries from this disk, add the exec option.
For Floppies, you should use the filesystem type of auto, make them user mountable (using the user option. You also need to use noauto, to prevent Linux from mounting this disk on boot.
CD-ROMS should use the same options as floppies, except with the addition of ro for readonly, indicating that you won't be able to write to this disk.
Backup Days
The fifth column is a number representing the number of days, since you previously backed up the disk. This column can be used by the system admin to tell when he needs to backup, a script or a backup program.
File System Check
The final column is exclusively for ext2 disks, and when they should be checked. Your root filesystem (/) should use a 1 to indicate checking upon boot. Any other ext2 partitions or disks, should use a 2 to indicate a fsck on boot (if mounted upon boot) or upon mount.
