[SOLVED] How to process a file and replace a pattern with the line number

Issue

So, I'm trying to design a little program and I'm planning to use a config file and have the ID be the line number. Here's a small example .conf file:

ID=_PATTERN_ 
STATE=window 
DIR=_code 
GEO=1200x250+0+32 
CMDS=cd home

I'm trying to find a way to replace _PATTERN_ with the line number. This is mainly because the ID isn't important to the person creating the file, just for the processing script that uses the .conf. So I figured, just make the ID autogenerated through some preprocessing. I was thinking of using sed or awk but I'm not really sure what to look up to get the answer to this.

Solution

At the shell prompt:

$ awk '{ gsub(/_PATTERN_/, FNR); print }'
_PATTERN_
1
_PATTERN_ _PATTERN_
2 2
foo _PATTERN_
foo 3

Answered By - Kaz

Answer Checked By - Dawn Plyler (WPSolving Volunteer)