shell script comparison for two file(text) character wise

Hi All,

This forum helped me a lot! Thanks for your help.

Well, Again I am in problem I need to write a shell script which can compare two files(text files) character wise.

eg.
underscore is space.
------FILE 1---------------
A_B_C
D_E_F
G_H_I
------------------------------

--------FILE 2--------------
A_BC
D_E_F
GH__I
---------------------------

Output should be
_C -> C_
_H -> H_

Actual problem: I need to write a shell script which can give me difference character by character not by line (using comm)

Please HELP HELP!

Thanks,
Vaibhav

diff?
cmp?

Both will more or less give you the information.

But you might have to post-process the results with something else to get the desired format.

Originally Posted by vaibhavs17

Actual problem: I need to write a shell script which can give me difference character by character not by line (using comm)

Personally, I would rather eat glass than use bash for this but here is a starting point:

Code:

#!/bin/bash

i=0
while read line; do
	file[$i]=$line;
	i=$((i+1));
done < "test.sh"

i=0
while [ $i -lt ${#file[*]} ]; do
	j=0
	while [ $j -lt ${#file[$i]} ]; do
		echo ${file[i]:$j:1};
		j=$((j+1));
	done;
	i=$((i+1));
done;

Doesn't that look like fun? This stores "test.sh" in an array of lines, then prints each line one character at a time, like:


#
!
/
b
i
n
/
b
a
s
h


You cannot have multi-dimensional arrays in bash, but if an array element is a string you can deal with the individual characters in a string. For more on arrays:

Arrays

Remember: bash is whitespace sensitive!!!! Also, if you run this script on itself notice what happens with the asterisk on line 10 -- demonstrating shell scripts can be dangerous in unpredictable ways (this one isn't dangerous).