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From: merce@iguana.uucp (Jim Mercer)
Newsgroups: comp.lang.c
Subject: help with popen()
Message-ID: <1991Feb6.053237.11051@iguana.uucp>
Date: 6 Feb 91 05:32:37 GMT
Sender: merce@iguana.uucp (Jim Mercer)
Distribution: na
Organization: Ed (the iguana) Memorial Society
Lines: 39

a snippet of code:


	char	*p_value;
	FILE	*F_pipe;
...
[	p_value points to "no_such_file"   ]

	F_pipe = popen(p_value, "r");
	if (F_pipe == NULL)
		{
		fprintf(stderr, "failure opening pipe (%s)\n", p_value);
		return(!OK);
		}
...
	pclose(F_pipe);

intention:

open a pipe to a process, use fgets to read input, warn user on pipe failure.

question:

when i run this on my 3b1, CTIX (SysV 2+ sort of),
i get "sh: no_such_file: not found" on stderr.
but, according to the if, F_pipe is not NULL.

works fine if p_value points to an existing command.

according to my documentation (Advanced Programmer's Guide to Unix System V,
McGraw-Hill), "popen() returns NULL if _command_ cannot be started".

am i doing something wrong?
is my popen() broken?

-- 
[ Jim Mercer   work: jim@lsuc.on.ca  home: merce@iguana.uucp  +1 519 570-3467 ]
[     "I am pro-military.  I am not pro-war.  There is a big difference"      ]
[                             -- Louise Mandrell (Toronto Sun)                ]