On Fri, Jun 27, 2025 at 08:51:10AM -0700, Jim Meyering wrote: > > > > > > [1] https://pubs.opengroup.org/onlinepubs/9799919799/utilities/tail.html > > > > tail -r comes from the BSDs. > > Also the BSDs don't have tac(1) which overlaps in functionality quite a bit. > > I'm a bit surprised -r was added by POSIX, but fair enough. > > "Surprised" is putting it lightly. I am disappointed and am tempted to > push back and to delay encumbering GNU tail with -r. > That is an option no GNU system needs, since they've all had tac since > before 1992-era textutils. > > I've Cc'd Eric Blake, in case someone wants to propose adding tac to > POSIX in spite of the fact that the BSDs still lack it.
I'll bring up this topic at the next Austin Group meeting. At any rate, it looks like tail -r was added due to this bug report in 2014 (sadly, it is no longer an option to ask Jorg Schilling why he wanted it standardized) https://www.austingroupbugs.net/view.php?id=877 But I did ask at the time (with no answer) why we went with 'tail -r' instead of 'tac'. -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
