Date: Fri, 31 May 2013 00:30:31 +0200 From: Jilles Tjoelker <jilles@stack.nl> To: =?iso-8859-1?Q?V=E1clav?= Zeman <vhaisman@gmail.com> Cc: rank1seeker@gmail.com, Reid Linnemann <linnemannr@gmail.com>, hackers@freebsd.org Subject: Re: /bin/sh => STDIN & functions, var scope messing Message-ID: <20130530223031.GA1672@stack.nl> In-Reply-To: <CAKw7uVjty2cJXT_QmexxKdRQyiKoHYMK1E-TjSHa5TCX1S8Bbg@mail.gmail.com> References: <20130527.194235.693.1@DOMY-PC> <CA%2B0MdpOcz7aw03HCrbxZVt1cnWdR4shqWaEfBrQkCpPnbgXLPQ@mail.gmail.com> <CAKw7uVjty2cJXT_QmexxKdRQyiKoHYMK1E-TjSHa5TCX1S8Bbg@mail.gmail.com>
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On Tue, May 28, 2013 at 11:48:47AM +0200, Václav Zeman wrote: > On 27 May 2013 21:58, Reid Linnemann wrote: > > from SH(1) > > "Note that unlike some other shells, sh executes each process in a pipe- > > line with more than one command in a subshell environment and as a > > child > > of the sh process." > > I'm taking this to mean that redirecting to sh_f has sh_f execute in > > a subshell in which global_scope_var changes, but the original > > shell's copy is uncahnged. > Curious. Which of the two behaviours is POSIXly correct? Both. As per XCU 2.12 Shell Execution Environment, each command in a multi-command pipeline may or may not be executed in a subshell environment. Behaviour different from our sh is most often encountered in the various versions of the real Korn shell (ksh88 and ksh93), which execute the last command in a pipeline in the current shell environment. If things like jobs | cat work, that can also be explained using this rule. -- Jilles Tjoelker
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