Linux: Checking the fstab prior to a reboot

One of the joys of working on a server from a remote location is dealing with the issue caused by a broken /etc/fstab file. Even the best admins make mistakes and mistakes in that file can lead to a server that won't boot.

Which is fine; if you have an IP-based KVM where you can get console access without actually being at the facility. But not so great when a screwed up fstab file requires you to go physically visit the location.

So how do we verify that our fstab file makes sense prior to a reboot? The answer lies in the mount command. There are (3) useful options that can be passed to the mount command which will help us check the fstab file prior to a reboot.

-f - FAKE IT (Causes everything to be done except for the actual system call). This tells mount to do everything, but don't actually change anything.

-a - Mount all filesystems mentioned in fstab.

-v - Be verbose about it.

Here's an example where everything is fine and dandy.

# mount -fav
mount: /dev/md0 already mounted on /boot
mount: devpts already mounted on /dev/pts
mount: tmpfs already mounted on /dev/shm
mount: proc already mounted on /proc
mount: sysfs already mounted on /sys
mount: /dev/md4 already mounted on /var/log
nothing was mounted

Same example, except that I screwed up the name of /dev/md4 in the fstab file:

# mount -fav
mount: /dev/md0 already mounted on /boot
mount: devpts already mounted on /dev/pts
mount: tmpfs already mounted on /dev/shm
mount: proc already mounted on /proc
mount: sysfs already mounted on /sys
/dev/md4x on /var/log type ext3 (rw,noatime)
nothing was mounted

Now, there's probably a better way to do this, but this serves as at least a moderate check against shooting yourself in the foot.