12 Sep
2014
12 Sep
'14
5:33 a.m.
On Thu, Sep 11, 2014 at 11:15:55PM -0400, Noel Chiappa wrote:
Rob (different rob) and I made a command line expr like thing, can't
remember why that did the same trick of shoving stuff (in our case it
was argv) into a pipe and then running yyparse().
It's at www.mcvoy.com/lm/af.shar
Still builds though it is from 1988.
--
---
Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm
From: Mark
Longridge <cubexyz(a)gmail.com>
I have a version of Unix v6 that has a file
called /usr/doc/bc that
describes bc at length
Oh, right, I missed that. I'm a source kind of person... :-)
Speaking of using a pipe to an existing command, I originally mis-read the
code to think there was only _one_ process involved, and that it was buffering
its output into the pipe before doing the exec() itself - something like this:
pipe(p);
write_stuff(p[1]);
close(0);
dup(p[0]);
close(p[0]);
close(p[1]);
execl("/bin/other", "other", arg, 0);
Which is kind of a hack, but... it does avoid using a second process, although
the amount of data that can be passed is limited. (IIRC, a pipe will hold at
most 8 blocks, at least on V6.) Did this hack ever get used in anything?