comment out lines in /fstab with bash script

Question

I need a bash script command to look in /etc/fstab and find the line that contains a mount name "/mymount" and just puts a "#" at the beginning of the line to comment it out.

from this:

    /dev/lv_mymount /mymount  ext4    defaults        1 2

to this (with a #):

    #/dev/lv_mymount /mymount  ext4    defaults        1 2

Answer 1

Using sed:

sed -i '/[/]mymount/ s/^/#/' /etc/fstab

How it works:

• -i

  Edit the file in-place

• /[/]mymount/

  Select only lines that contain /mymount

  • s/^/#/

  For those selected lines, place at the beginning of the line, ^, the character #.

Using awk:

awk '/[/]mymount/{$0="#"$0} 1' /etc/fstab >/etc/fstab.tmp && mv /etc/fstab.tmp /etc/fstab 

How it works:

• /[/]mymount/ {$0="#"$0}

  For those lines containing /mymount and place a # at the beginning of the line.

• 1

  This is awk's cryptic shorthand for "print each line."