cmp
|
cmp
is another program for comparing files.
(There's also a GNU version on the CD-ROM.)
It's a lot simpler than
diff
(
28.1
)
;
it tells you whether
the files are equivalent, and the byte offset at which the first
difference occurs. You don't get a detailed analysis of where the two
files differ.
For this reason,
cmp
is often faster,
particularly when you're comparing
ASCII (
51.3
)
files: it doesn't have to
generate a long report summarizing the differences.
If all you want
to know is whether two files are different, it's the right
tool for the job. |
It's worth noting, though, that
cmp
isn't
always
faster.
Some versions of
diff
make some simple checks first, like
comparing file length. If two binary files have different lengths,
they are obviously different; some
diff
implementations will
tell you so without doing any further processing.
Both
diff
and
cmp
return an
exit status (
44.7
)
cmp
that shows what they found:
Within a shell script, the exit status from
diff
and
cmp
is often more important than their actual output.