From mboxrd@z Thu Jan 1 00:00:00 1970 From: wkt@tuhs.org (Warren Toomey) Date: Wed, 4 Jan 2017 07:53:10 +1000 Subject: [TUHS] Pipes in the Third Edition Unix In-Reply-To: References: Message-ID: <20170103215310.GA26242@minnie.tuhs.org> On Tue, Jan 03, 2017 at 10:54:57PM +0200, Diomidis Spinellis wrote: > Peter Salus writes "The other innovation present in the Third Edition was > the pipe" ("A Quarter Century of Unix", p. 50). Yet, in the corresponding > sys/ken/sysent.c, the pipe system call seems to be a stump. The Third edition was still written in assembly code. The Fourth edition was the first to be rewritten in C. So there was a time when both existed in parallel. > 1, &fpe, /* 40 = fpe */ > 0, &dup, /* 41 = dup */ > 0, &nosys, /* 42 = pipe */ > 1, ×, /* 43 = times */ This code, from the nsys kernel, clearly shows this. The kernel was being rewritten in C. The C version had not yet caught up with the functionality in the assembly version of the kernel, which did have pipes. Cheers, Warren