Effects of /etc/fstab file!

 
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Operating Systems Linux Red Hat Effects of /etc/fstab file!
# 8  
Old 07-02-2012
Have you no backups? or at least a copy of config files...
It will be difficult to guess the entries of your fstab unless you havent done anything special... that means accepted the defaults at install time.
# 9  
Old 07-03-2012
No I didn't.
But I am amusing that Linux don't have any preliminary feature for the back-up.
It can't be that vulnerable.
# 10  
Old 07-03-2012
If you delete your registry Hive files, Windows won't boot properly either. How vulnerable, right?
# 11  
Old 07-03-2012
Unlike your registry however, it can be rewritten from scratch by hand in a reasonable amount of time. Use things like fdisk and such to find all your partitions, mount them in a restore disk to figure out which is which, and write entries into your fstab like so:

Code:
# /etc/fstab: static file system information.
#
# noatime turns off atimes for increased performance (atimes normally aren't
# needed; notail increases performance of ReiserFS (at the expense of storage
# efficiency).  It's safe to drop the noatime options if you want and to
# switch between notail / tail freely.
#
# See the manpage fstab(5) for more information.
#

# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>

# NOTE: If your BOOT partition is ReiserFS, add the notail option to opts.
/dev/sda1               /boot           ext2            noatime         1 2
/dev/sda3               /               ext3            noatime         0 1
/dev/sda5               /var            ext3            noatime         0 1
/dev/sda6               /usr            ext3            noatime         0 1
/dev/sdb1               /home           ext4            noatime         0 1
/dev/sda2               none            swap            sw              0 0

/dev/cdrw               /mnt/cdrom      iso9660         noauto,ro,user  0 0
/dev/fd0                /mnt/floppy     auto            noauto,user     0 0

# NOTE: The next line is critical for boot!
proc                    /proc           proc            defaults        0 0

# glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for
# POSIX shared memory (shm_open, shm_unlink).
# (tmpfs is a dynamically expandable/shrinkable ramdisk, and will
#  use almost no memory if not populated with files)
shm                     /dev/shm        tmpfs           nodev,nosuid,noexec    0 0

Of course, yours won't be exactly the same. The partition types, device names, and numbers will all differ, not to mention you won't have the same layout either. But that's how it works.
# 12  
Old 07-04-2012
And when you've written the new fstab file, don't forget to back it up! Smilie

The possibility of overwriting important files is one of the reasons I tell new Linux admins to avoid routinely using the root account, but instead creating an account with sudo privileges for normal day-to-day stuff, at least it doesn't let you change important files without using sudo, so there isn't the same possibility of accidentally overwriting system files.
# 13  
Old 07-06-2012
For future reference, if anything like this should ever happen again, typing
Code:
mount

will give you the info you need to rewrite the fstab. I would suggest never rebooting or restarting after overwriting something critical - Unix-style systems are easy to get under the hood of, but not always so forgiving of human error.
Code:
cat /etc/mtab

would also be helpful.
Assuming you don't have a backup, you'll probably need to run fdisk/cfdisk and get an idea of what partitions are set up, and go from there.
# 14  
Old 08-22-2012
Quote:
Originally Posted by nixhead
# blkid /dev/vda5 > /etc/fstab
Quote:
Originally Posted by nixhead
But I am amusing that Linux don't have any preliminary feature for the back-up.
It can't be that vulnerable.
It would have been helpful if immediately upon submission of that command the shell had forked an assistant:
Quote:
Clippy: "nixhead, it looks like you are about to truncate a critical system file. Please choose one of the following options: Abort, Cancel, Shutdown.
Smilie

All joking aside, that won't be your last mistake. They happen to everyone from time to time. The difference is whether you're prepared to recover. You should not only have backups but a tested recovery procedure.

Regards,
Alister
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