How to read and update(increment) a value in a file with shell commands

I have a certain file which contains many contents, including a line from the format (for example)

ABC = “x12”

What I need to do is to increment the value, so that after the command it will be

ABC = “x13”

The file itself needs to be updated, no need to create a new file or something similar.

I would appreciate if someone do this for me.

Answer

Here is my quick-and-dirty solution using sed:

sed -i 's|([a-zA-Z]* = )"([A-Za-z]+)([0-9)]+)(")| echo 1 \"2$(expr 3 + 1 )\" |ge' ~/file.txt

Example:

$ cat ~/file.txt
ABC = "x12"
$ sed -i 's|([a-zA-Z]* = )"([A-Za-z]+)([0-9)]+)(")| echo 1 \"2$(expr 3 + 1 )\" |ge' ~/file.txt
$ cat ~/file.txt
ABC = "x13"
$ # works for other keys as well:
$ cat ~/file2.txt
KEY = "y12"
$ sed -i 's|([a-zA-Z]* = )"([A-Za-z]+)([0-9)]+)(")| echo 1 \"2$(expr 3 + 1 )\" |ge' ~/file2.txt
$ cat ~/file2.txt
KEY = "y13"