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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: shell stderr in popen()
Message-ID: <7928@mimsy.UUCP>
Date: Sun, 9-Aug-87 13:27:56 EDT
Article-I.D.: mimsy.7928
Posted: Sun Aug  9 13:27:56 1987
Date-Received: Sun, 9-Aug-87 23:05:13 EDT
References: <4511@sunybcs.UUCP>
Distribution: na
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 22
Keywords: shell popen stderr redirection

>In article <124@foobar.UUCP> tw@foobar.UUCP (Tom Walsh) writes:
>>[Using] popen(command, "r") ... i would like to dispose quietly of
>>the shell's complaint:
>>  sh: command: not found

In article <4511@sunybcs.UUCP> ugbinns@sunybcs.uucp (Leonard Binns) writes:
>Did you ever try:
>	popen("/usr/bin/mynewcommand -flags 2>& /dev/null", "r");

This will not do it.  (For one thing, it is syntactically invalid.)
The shell prints `sh: <x>: not found' to the *shell's* standard
error output, before any redirection.  There are several possible
solutions, but the easiest is to add one level of indirection:

	(void) sprintf(expandcmd, "sh -c '%s' 2>/dev/null", command);
	iop = popen(expandcmd, "r");

Note that this assumes `command' has no single quotes embedded in
it.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris