On Apr 24 2019, Greg Wooledge <wool...@eeg.ccf.org> wrote: > On Wed, Apr 24, 2019 at 06:47:41AM -0600, Ian Neal wrote: >> At what point is a subshell being invoked? There's no pipeline, command >> substitution, coprocess, background process, or explicit () subshell here, >> which are the only cases a subshell should be created. Otherwise, the >> entire operation should be evaluated by the main shell. Arithmetic >> expansion is not in that list. > > The context got snipped but IIRC it was something like > > /bin/true > $((n++)) > > The /bin/true forces the use of an external command, which means a subshell > is forked. The redirection occurs in the forked subshell.
But the expansion isn't required to be performed in the subshell. I don't see POSIX having any wording to require one or the other. Doing the expansion before the fork looks reasonable, even if only to make it consistent with builtins. Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."
