Thanks again for checking all that.

Assaf Gordon wrote:

> On NetBSD 7.0, 6.1.4, One test fails (zgrep-f) perhaps due to filename issues?


No, NetBSD's mktemp command is incompatible with GNU's, in terms of the 
interpretation of -t. The simplest fix is to stop using mktemp's -t option 
(which has been "deprecated" in the GNU version for many years anyway).

> I'm adding Alpine Linux to my test suite ( https://alpinelinux.org/ ).
> ...
> On this system, zdiff check fails because busybox's diff does not support the "-c" option

Wow, *that* is stripped down. Well, it shouldn't be that hard to port to. Does 
the attached patch fix the problem (as well as the NetBSD problem)?