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I'm on Ubuntu 14.04.

I pasted something incorrect (from a tutorial) into my /etc/fstab file. As a result, the root file system will not mount when the machine boots up.

I know what needs to be fixed in /etc/fstab, but I cannot save the file (or any file) because the system boots as read only.

As root, I tried:

mount -o remount,rw /

to no avail. The error message cited the section of bad options that I pasted into /etc/fstab.

I read some stuff about booting into single user mode by adding 'single' to the end of the kernel parameter. I can't seem to find the kernel parameter. On the grub menu, I highlight Ubuntu and press 'e' which brings up a file with some sort of configuration, but there is no 'kernel' parameter to be found.

I'm relatively new to linux. Can anyone help me figure out a way to fix my /etc/fstab file so that Ubuntu will boot normally?

  • Can you make a live USB and boot to it? The kernel parameter is the line that begins with linux .... – muru Feb 15 '15 at 22:09
  • ah thanks for pointing out which is the kernel parameter. i will try to add 'single' to the end of it and follow instructions from there. – Daveh0 Feb 15 '15 at 22:31
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    mount -o remount,rw / should work. What are the exact error messages? – Gilles 'SO- stop being evil' Feb 15 '15 at 22:38
  • @Gilles - it worked after I booted into single user mode – Daveh0 Feb 15 '15 at 22:55
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The way you have tried the mount command still uses the information from /etc/fstab.

Try the following version and it should work independent of the contents of /etc/fstab:

mount -o remount,rw /dev/sdb6 /

Note: Instead of /dev/sdb6, use whatever device is valid for your drive.

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15

To get things back to where they should be, I:

  1. Highlighted 'Ubuntu' at the boot menu
  2. hit 'e' to edit the configuration
  3. in the line starting with linux=, I switched the 'ro' to 'rw' and added the word 'single' at the very end of the line
  4. hit f10 to boot
  5. once it booted, as root, I did:

    mount -o remount,rw /
    
  6. as root, I edited /etc/fstab to get it where it needed to be

  7. rebooted normally and everything seems to be fixed
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