Compare two files
 

What is the best program for it

I am using cmp but that does not seam to say line 2 is different to the other files

Just get EOF on etc/passwd-

mailman:# cmp /etc/passwd /etc/passwd-
cmp: EOF on /etc/passwd-


Anyone else have a program that comparies files. have to be able to use it in shell


"I do not have a gui"

The diff command may be what you need. It can report on the line by line differences between 2 text files. It only tells you whether or not the 2 files are different if they are binary though.
I usually use the -u switch which outputs in a format I prefer. However, -y outputs differences side by side which is also useful. Try the man page - if it doesn't explain it clearly, let me know