> On 2016/10/11 13:35, Theo de Raadt wrote: > > > Jan Stary <[email protected]> writes: > > > > > > > The diff below makes head(1) recognize `-' > > > > as a name for the standard input, > > > > as many other utilities do. > > > > > > Makes sense to me. The following points could be improved IMO: > > > - using strcmp sounds cleaner than those char comparisons > > > - I don't think the man page bits are needed. Utilities that read from > > > stdin are supposed to support `-'. I'm not sure whether the extra > > > example is really helpful. > > > - should we avoid closing stdin (multiple times)? Even though our > > > fclose(3) seems to cope with this, it seems that neither the > > > C standard nor POSIX offer such a guarantee. > > > > Do standards permit that extension? > > > > This is command used in scripts. Scripts are often portable. If one > > operating system has an extension, but others don't, then those > > scripts become unportable to use use of these extensions. > > > > I'm not raising a new argument here, it's been raised numerous times > > when it comes to commands commonly used in scripts. > > > > So consider that first. > > Standards permit it but don't require it, so it's already a mess. > > "The standard input shall be used if no file operands are specified, and > shall be used if a file operand is '-' and the implementation treats the > '-' as meaning standard input. Otherwise, the standard input shall not > be used. See the INPUT FILES section." > > http://pubs.opengroup.org/onlinepubs/9699919799/utilities/head.html > > Same for tail, of course.
Well in that case, support for "-" is probably increasing compatibility rather than diminishing it.
