Path: utzoo!attcan!uunet!lll-winken!lll-tis!oodis01!uplherc!sp7040!obie!wsccs!terry
From: terry@wsccs.UUCP (Every system needs one)
Newsgroups: comp.unix.wizards
Subject: Re: how can I determine controlling tty if no file descriptor is open onto it?  (System V r[23])
Summary: do it first
Message-ID: <550@wsccs.UUCP>
Date: 28 May 88 05:53:36 GMT
References: <2658@ttrdc.UUCP> <2661@ttrdc.UUCP>
Lines: 24

In article <2661@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes:
>I am trying to write a program UNDER SYSTEM V RELEASE 2 AND 3 which
>disassociates itself from the controlling terminal (using setpgrp() after
>redirecting all file descriptors still open onto the terminal, into a file),
>tries to exec() a machine binary or shell script, and if that doesn't work
>sends an error message to the terminal and exits.
>...
>However, I am having a problem with always getting an error message back to
>the terminal from which the command was issued.

Use ttyname() before leaving you program clueless.  If you are redirecting
at a shell level, don't; use freopen() after using ttyname().  This will
leave your poor program clueless just as efficiently.  Or use getpgrp()
before using setpgrp().

"exec()" a shell script?  Try an execl() of 'sh -c script' instead, unless
your exec() is weird.


| Terry Lambert           UUCP: ...{ decvax, ihnp4 } ...utah-cs!century!terry |
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| SLC, Utah                                                                   |
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