On Tue, Jul 01, 2025 at 07:07:45PM +0200, Bernhard Voelker wrote: > On 6/28/25 00:21, Pádraig Brady wrote: > > I wouldn't be rushing to implement it TBH. > > Furthermore, -r clashes with the existing -f,--follow ... hence it's even more > surprising that POSIX does not specify what should happen for those logically > conflicting modes.
Remember, the POSIX synopsis lines lists two distinct invocation styles: tail [-f] [-c number|-n number] [file] tail -r [-n number] [file] which means undefined behavior from the POSIX point of view if -f and -r are ever attempted at the same time. Therefore, whatever GNU decides to do on that combo (preferably, diagnose it early with an error and exit, since I can't figure out anything else useful it could do) will not violate POSIX. -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
