Xref: utzoo comp.lang.c:38928 comp.unix.sysv386:7651
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!tellab5!chinet!les
From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.lang.c,comp.unix.sysv386
Subject: Re: How to execute 'sz' and 'rc' ?
Message-ID: <1991May01.054356.10098@chinet.chi.il.us>
Date: 1 May 91 05:43:56 GMT
References: <1991Apr29.221812.5038@nicedel.north.de>
Organization: Chinet - Chicago Public Access UNIX
Lines: 21

In article <1991Apr29.221812.5038@nicedel.north.de> nyse@nicedel.north.de (Hermann Behrens) writes:
>	if((pid = fork()) == 0)  {
>		close(fp);
>		close(0);
>		open("/dev/ttyF00", O_RDONLY | O_NDELAY);
>		close(1);
>		open("/dev/ttyF00", O_WRONLY | O_NDELAY);
>/* I think, that the bug is in the redirecting of stdin and stdout,
>but where is the bug?? */
>		execl("/bin/sh", "sh", "-c", "sz a_file",NULL);

On the machines I use, leaving O_NDELAY set will cause very strange
things to happen when you try to write to a device and reads will
complete when no data is present.  I'd suggest leaving out the
O_NDELAY on the open if you have reason to expect that carrier
is already up (but you might want to set an alarm to bail you out
just in case).  Or, use fcntl() to turn it off after the open before
you let another program try to access the line.

Les Mikesell
  les@chinet.chi.il.us