Is cmp faster than diff -q? In a recent Ask Ubuntu question on checking whether some files have differing content, I saw a comment stating that, if the differing sections didn't matter, `cmp` would be faster than `diff`. This Stack Overflow answer concurs, giving the reason that `cmp` would stop at the first differing byte. However, GNU `diff` has the `-q` (or `--brief`) flag, which is supposed to make it `report only when files differ`. It would seem logical that GNU `diff` would also stop comparing once any difference is found (like `grep` would stop searching after the first match when `-l` or `-q` is specified). Is `cmp` truly faster than `diff -q`, in the context of Linux systems, which are likely to have the GNU version?

Prompted by @josten, I ran a comparison on the two. The code is on GitHub. In short:

![user-sys](

![real](

The User+Sys time taken by `cmp -s` seemed to be a tad more than that of `diff` in most cases. However, the Real time take was pretty much arbitrary - `cmp` ahead on some, `diff` ahead on some.

**Summary:**
Any difference in performance is pure coincidence. Use whatever you wish.