From mboxrd@z Thu Jan 1 00:00:00 1970 From: clemc@ccc.com (Clem Cole) Date: Thu, 14 Jul 2016 09:23:04 -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: Could you be confusing the fact the true and false were implemented by external commands in some early shell's On Thu, Jul 14, 2016 at 9:18 AM, 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. > > The only external command I found was glob, which performed wildcard > expansion. > > Am I missing something? Was this implemented in a version that was never > released? If so, does anyone know how this implementation worked? (Nested > commands might require holding some sort of globally accessible stack.) > -------------- next part -------------- An HTML attachment was scrubbed... URL: