From mboxrd@z Thu Jan 1 00:00:00 1970 From: schoedel@kw.igs.net (schoedel@kw.igs.net) Date: Thu, 14 Jul 2016 10:11:35 -0400 Subject: [TUHS] Shell control through external commands In-Reply-To: <4fcf31ef-50af-10b5-0c34-ad647ed10a4e@aueb.gr> References: <4fcf31ef-50af-10b5-0c34-ad647ed10a4e@aueb.gr> Message-ID: <20160714141112.M89671@kw.igs.net> On Thu, 14 Jul 2016 16:18:43 +0300, Diomidis Spinellis wrote > I remember hearing that originally the Unix shell had control structures > (e.g. if, while, case) implemented through external commands. However, > I can't see this reflected in the source code. The 7th Edition > Bourne shell has these commands built-in (usr/src/cmd/sh/cmd.c), while > the 6th Edition (usr/source/s2/sh.c) seems to lack them completely. http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/if.c http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/goto.c -- Kevin Schoedel VA3TCS