On 2020-12-13 at 12:03, The Wanderer wrote: > ps2pdf appears to be part of ghostscript. Neither its man page nor the > one for 'gs' (which it references) seem to contain any options for > setting these timestamps, preventing their creation, or doing similarly > with that UUID. > > > The Debian reproducible-builds project has a page on eliminating this > type of "multiple runs on the same input don't produce identical output" > issue more generally[1], which links to a page on doing so with PDFs > generated by Ghostscript specifically[2]. > > I'm not enough of an expert to follow that much further, but at a > glance, it looks like the solution is to patch Ghostscript; the patch > doesn't seem to have been accepted upstream, and it's not clear whether > or not it's (going to be) distributed in the Debian package. > > If you're not OK with handling that on your own end, then you may be out > of luck with this. > > [1] https://wiki.debian.org/ReproducibleBuilds/Howto > [2] https://wiki.debian.org/ReproducibleBuilds/PdfGeneratedByGhostscript On closer examination of that latter link, apparently it's possible to bypass the timestamps issue by using a command called 'faketime' (from a package of the same name), to tell the program that the system-clock time is set to something other than what it actually is. The UUID is generated based on time, but apparently it's done in a way that isn't affected by faketime, and that is what needs to be patched. So you can probably eliminate three of the five differences by just prepending 'faketime ' to your ps2pdf command. The other two will still probably need patching of ghostscript to fix, however, and the link to the patch from the above page seems to be dead. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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