On Thu, 10 Jul 2008 09:45 pm, Mel wrote: > On Thursday 10 July 2008 06:24:46 Malcolm Kay wrote: > > > > 9255 if { as_var=$as_ac_var; eval "test \"\${$as_var+set}\" = set"; }; > > > then > > > > I find this line somewhat strange as I've not been able > > to find documentation for the expansion of ${parameter+set} under the > > Bourne shell. (nor bash, nor ksh) > > ***************************************************** > > Presumably someone out there knows where to find it? > > ***************************************************** > > It's shorthand for ${paramter:+set}, so if unset, you get "", otherwise you > get "set": > $ echo ${foo+set} > > $ echo ${HOME+set} > set
So it appears; but is it stated anywhere that this shorthand is legitimate? I find it quite frequently arising from the GNU configuring tools but haven't found it elsewhere. Is it a deliberate shorthand or just a consequence of the way sh and bash happen to have been programmed? In other words is it a safe shorthand? Anyway thanks for the clarification, Malcolm > > _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"