On 03/22/2016 09:13 AM, Eric Blake wrote: > On 03/22/2016 06:43 AM, Ruediger Meier wrote: >> Hi, >> >> Is there any good reason why coreutils true and false are not POSIX? > > No, because coreutils' true and false ARE compliant with POSIX. > >> But coreutils true has --version and --help implemented. It needs >>> /dev/null redirection to work as expected. > > Not true. POSIX says that behavior is unspecified for 'true --help'. > Therefore, whatever coreutils does in that case does not violate POSIX. > > 'true -- --help', on the other hand, must be silent - but coreutils > obeys that rule.
Correction - POSIX says that 'true -- --help' is unspecified, so coreutils can do whatever it wants (and in that case, GNU coreutils opted to treat '--help' as an ignored operand, because the '--' ended the chance to treat it as an option). According to POSIX, the _only_ specified use of 'true' is without operands: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/true.html > SYNOPSIS > > true Any other arguments on the command line are extensions, and can behave however the implementation wants; portable apps will not be invoking 'true' with arguments, because they are no longer getting behavior mandated by POSIX. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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