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FSTAB and MTAB


These are some of those critical programs for your computer. Without these, your computer will not know where to find any of the partitions or drives on the computer. Goof this up and you can be dead in the water. Never make any changes without a good backup copy.

/etc/fstab

In this file there is a description of the various file systems. Commands like ¨fsck¨ and ¨mount¨ consult this file for the actions they take.
This looks like a complicated description of the files on your computer, but it is really simple if you break it down into the parts of each entry. Take a look below.
( OR :In order for certain programs to be able to determine where certain partitions are supposed to be mounted by default, the /etc/fstab file is used )




/dev/hdb1 / ext3 defaults 1 1
none /dev/pts devpts mode=0620 0 0
/dev/hdb6 /home ext3 defaults 1 2
none /mnt/cdrom supermount dev=/dev/hdc,fs=auto,ro,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
none /mnt/cdrom2 supermount dev=/dev/scd0,fs=auto,ro,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
none /mnt/floppy supermount dev=/dev/fd0,fs=auto,--,iocharset=iso8859-1,sync,codepage=850,umask=0 0 0
/dev/hda1 /mnt/windows vfat iocharset=iso8859-1,codepage=850,umask=0 0 0
none /proc proc defaults 0 0
/dev/hdb7 /usr ext3 defaults 1 2
/dev/hdb5 swap swap defaults 0 0
/dev/sda1 /mnt/memory_card auto user,iocharset=iso8859-1,kudzu,codepage=850,noauto,umask=0,exec 0 0




I will try to bring some clarity in there. Let´s only take the partitions, here for Linux : / and /home and swap. For Windows C:


< partition >< mount point >< file system >< mount options >< dump >< fsck order >
/dev/hdb1 . . . . / . . . . . . . . . . . .     ext3 . . . . . . . . . defaults . . . .   . . . 1 . . . . . . . . . 1
/dev/hdb6 . . . . /home. . . . . . .       ext3 . . . . . . . . . defaults . . . . .   . . 1 . . . . . . . . . 2
/dev/hdb5 . . . . swap . . . . . . . .     swap . . . . . . . .  defaults . . . .   . . . 0 . . . . . . . . . 0
/dev/hda1 . . . . /mnt/win_c             vfat . . . iocharset=iso8859-1,codepage=850,umask=0 0 0





For the CD-ROM and floppy drive:


none /mnt/cdrom . . supermount dev=/dev/hdc,fs=auto,ro,--,iocharset=iso8859-1,codepage=850,umask=0 0 0

none /mnt/floppy   supermount dev=/dev/fd0,fs=auto,--,iocharset=iso8859-1,sync,codepage=850,umask=0 0 0



You can see the CD-ROM and floppy have the same codes as the Windows partition because they are not Linux default.



For the memory card reader:


/dev/sda1 /mnt/memory_card auto user,iocharset=iso8859-1,kudzu,codepage=850,noauto,umask=0,exec 0 0





Two additional entries are ¨devpts¨ and ¨/proc¨

The devpts file system provides an interface to pseudo-terminal (pty) devices. It is typically mounted at /dev/pts.

The /proc filesystem is to provide an easy way to view kernel and information about currently running processes.

If you build Linux from scratch, you will have to write your own /etc/fstab file.



/etc/mtab

This file handles the mounted devices and is automatically updated by the mount command.
And it looks a bit similar to fstab but not the 100% same ( notice rw and ro for read/write and read only ) And it does only lists the mounted devices !



/dev/hdb1 / ext3 rw 0 0
none /proc proc rw 0 0
none /proc/bus/usb usbdevfs rw 0 0
none /dev devfs rw 0 0
none /dev/pts devpts rw,mode=0620 0 0
/dev/hdb6 /home ext3 rw 0 0
none /mnt/cdrom supermount ro,dev=/dev/hdc,fs=auto,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
none /mnt/cdrom2 supermount ro,dev=/dev/scd0,fs=auto,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
none /mnt/floppy supermount rw,sync,dev=/dev/fd0,fs=auto,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
/dev/hda1 /mnt/windows vfat rw,iocharset=iso8859-1,codepage=850,umask=0 0 0
/dev/hdb7 /usr ext3 rw 0 0
/dev/sda1 /mnt/memory_card vfat rw,nosuid,nodev,iocharset=iso8859-15,codepage=850,umask=0,user=julia 0 0




Next time we will do the ¨mount¨ and ¨umount¨ commands related to these /etc/fstab and /etc/mtab files.



Bruno


-- Jul 2 2003 ( Revised Dec 10 2005 ) --


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