Fstab – What Do the Last Two Fields in fstab Mean?

fstab

The last two fields on each line in fstab (dump and pass) are some numbers (usually, 0).

What do these numbers mean?

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
UUID=030ccf66-5195-4835-ba3e-f5d7a5403c05 /               ext4    errors=remount-ro 0       1

Best Answer

Copy/paste from man fstab:

The fifth field, (fs_freq), is used for these filesystems by the dump(8) command to determine which filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and dump will assume that the filesystem does not need to be dumped.

The sixth field, (fs_passno), is used by the fsck(8) program to determine the order in which filesystem checks are done at reboot time. The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno of 2. Filesystems within a drive will be checked sequentially, but filesystems on different drives will be checked at the same time to utilize parallelism available in the hardware. If the sixth field is not present or zero, a value of zero is returned and fsck will assume that the filesystem does not need to be checked.

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