cmp
[options
]file1
file2
Compare file1
with file2
. Use standard input if
file1
is -. See also comm and diff.
The exit codes are as follows:
0 Files are identical. 1 Files are different. 2 Files are inaccessible.
For each difference, print the byte number in decimal and the differing bytes in octal.
Work silently; print nothing, but return exit codes.
Print a message if two files are the same (exit code is 0):
cmp -s old new && echo 'no changes'