Command Line – How to Recover Accidentally Deleted /etc/fstab File

bootcommand linefstab

I accidentally deleted my /etc/fstab file by running sudo rm /etc/fstab. Without realising what I'd done, I shut down my Ubuntu OS.

Now I'm not able to boot.

My screen looks like this. In some cases, a purple screen appears. Please give me some solutions.

Best Answer

You have to recreate a new fstab file inside /etc directory and add an entry for your root partition, so that your Ubuntu os will boot.

Method 1:

Recreating /etc/fstab file via Recovery mode

Boot into Recovery mode and then drop to root shell.

Run sudo blkid command to know the UUID of your /(root) partition.It will show something like this,

/dev/sda1: UUID="52e062e0-716c-4828-9bf1-05b93fdaef93" TYPE="ext4"
/dev/sda1: UUID="2F4DAFCF02D7EBEB" TYPE="ntfs" 
/dev/sda3: UUID="039E0CF305398945" TYPE="ntfs" 
/dev/sda5: UUID="C68C57908C5779BF" TYPE="ntfs"

From the sudo blkid output, identify your root ext4 partition and note down its corresponding UUID.
Now mount your / partition in Read Write Mode by running the below command.Please note that the simple mount / command for mounting your root partition won't work because of the deletion of /etc/fstab. So, if your / was /dev/sda1, run this command:
```
mount -t ext4 -o rw,remount /dev/sda1 /
```
The above command will mount your / partition in read write mode.Run the below command to create a new fstab file inside /etc with the appropriate line to mount your /. In the example above, my / has UUID=52e062e0-716c-4828-9bf1-05b93fdaef93, so I would run:
```
echo "UUID=52e062e0-716c-4828-9bf1-05b93fdaef93 / ext4 errors=remount-ro 0 1" > /etc/fstab
```
Exit from the root shell and boot your Ubuntu OS, it will surely bootup.

Method 2

Recreating /etc/fstab file via Ubuntu live disk

Boot ubuntu live disk.
Run sudo blkid command and note the installed Ubuntu partition's device id and the UUID.

Mount your root partition,

 sudo mkdir /media/ubuntu
 sudo mount /dev/sdaX /media/ubuntu

Now go into the /media/ubuntu via nautilus and create a fstab file inside /etc.

On that fstab file, add an entry for your root partition like below.

 UUID=52e062e0-716c-4828-9bf1-05b93fdaef93 / ext4 errors=remount-ro 0 1

Save that file.And boot into your installed Ubuntu.

Note: My root partition's UUID was given above.Please give your's.After booting into your installed Ubuntu OS, don't forget to add fstab entry for your swap partition.

Before you start:

It's always a good idea to work from a copy of your deleted data, so copy your entire disk before you begin
If you cannot, boot from a Live-USB/DVD before you begin.
If you cannot, know that by each and every single byte you write to your disk right now, one byte of one of your deleted files will be overwritten! (i.e. by installing PhotoRec and TestDisk, some deleted files will be overwritten by the applications that you're going to install if you continue!).

What are the main differences between TestDisk and PhotoRec?

TestDisk is a lot more efficient than PhotoRec. The problem with TestDisk is that it doesn't always recover all deleted files. If you accidentally reformat a partition, TestDisk can recover thousands of files without missing a single file, but if you deleted a file by sending it to the Trash and then emptying the Trash, TestDisk can't always recover it.

So use TestDisk first, and if you recovered all of the deleted files with TestDisk, then you're done. If you recovered most of the deleted files with TestDisk, you can decide whether you're done or not. If you're not done after running TestDisk, you can try recovering the deleted files using PhotoRec.

PhotoRec can selectively recover files based on their filetype(s), but PhotoRec / TestDisk can't selectively scan an individual directory for lost files unless you had mounted a whole hard drive partition as this directory. In some cases, the filename is stored in the file itself. PhotoRec tries to recover the filename in this case, but most of the time PhotoRec can't recover the filenames.

Recover files based on filetype using PhotoRec

Install TestDisk from the Ubuntu Software Center.
```
 sudo apt-get install testdisk
```
Launch PhotoRec.

Open a terminal and launch photorec (as root).
```
 sudo photorec
```
Select hard disk.
Select partition type.

If your hard disk has Linux partitions, then select [Intel].
Select filetype option.

Move to [File Opt] and press Enter. Here you can disable all file types by pressing s. Use space to toggle the check button. Select filetype(s) to recover. For Perl you can select pl for Perl script or pm for Perl module.
Select options.

Photorec also has a list of different options. Under normal circumstances you don’t need to modify them.
Select partition.

Move the selector up or down to the partition from which you have removed the file(s). Then select [Search] and press Enter.
Select filesystem type.

If you are using Linux, it's going to be ext2/ext3/ext4, so the default selection is ext2/ext3. Otherwise if you are recovering files from a partition formatted as FAT or NTFS select Other.
Select space for analysis.

Select Free if you didn’t write to that partition after removing the particular file, otherwise select Whole.
Select a directory for the recovered files

Select the path where the recovered files will be stored. Then press Y.

Photorec will show how many files it has recovered.

_{Source: revised from How To Recover Deleted Files in Linux Using Photorec}

Fstab Edit Crashed System – How to Fix

Boot your system using a live USB
Use Disks to determine the name of your system partition (probably sda1)
Open a terminal window
Mount the system partition by typing the command sudo mount /dev/sd__ /mnt where sd___ is sda1 or whatever the system partition is
Fix fstab using the nano editor sudo nano /mnt/etc/fstab. Probably just delete the lines you added, or do whatever you need to reverse your changes
Reboot