Shell Programming and Scripting

I have a script that outputs a file in the below format

Code:

group1:user1,user2,user3, user4
group2:user2, user4, user5
group3: user1, user6, user7

If there is a change in /etc/passwd with addition/deletion of users, then the next run of the script will output the file with the changes.

How can I have my script compare the 2 versions of the files and also show the changes(addition/deletion of users) in the new file

Please use code tags as reuqired by forum rules!

Before we start guessing please provide a sample (in code tags) of the output you desire.

I tried using the diff command, it tells me the files have been changed. But, it does not give me the exact changes when I use them in my script

Code:

diff final_op.txt final_op.txt_prev` 2>/dev/null
if [ $? -eq 0 ]
then
  echo " Files unchanged"
else
  echo "File contents have changed"
fi

How can I get the exact changes when I use diff in a script? Thanks for your help

That marked red '`' is a mistype?

The logic of the script is giving you a result that it is being interpreted erroneously. Whether the files are equal or different the exit status of diff is going to be successful (0). If the files compares equal, there's not output and your code is going to say: echo " Files unchanged"

---------- Post updated at 09:18 AM ---------- Previous update was at 08:45 AM ----------

By the way, the default of diff is that if both files are identical nothing is output to the stdout. If there are differences, then it outputs showing what changes needs to be done to make them equal.
diff -s: -s flag will report with output as well if files are equal.

man diff: does show more details of what can be done with it.