On 04/06/2013 04:27 PM, Bob Proulx wrote: > Pádraig Brady wrote: >>> - && chmod -w $@-t \ >>> + && chmod a-w $@-t \ >> >> I'll apply that fix. > > I think it is always a good idea to use 'a' when there isn't any other > specific reason to do anything different. Or put the reverse way, > whenever I see a naken "-[rwx]" then I am suspicious of the action. > Because it masks with umask and is almost never what is desired.
Actually, POSIX says that: chmod -w foo is undefined (that is, an argument with a leading - is interpreted as an option rather than as a mode string, but chmod is NOT required to support a -w option, even though many implementations support it as an extension). Meanwhile, POSIX requires that chmod -- -w foo is required to mask with umask. In fact, in coreutils, we exploit the fact that chmod -[rwx] is undefined, in order to emit warnings if the resulting change did not disable all bits. Using a-w instead of the undefined '-w' or the well-defined but confusing '-- -w' is indeed the right way to fix things. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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