Nagios Support Forum

Hi,
I'm trying to write a plugin and having some trouble w/ spopen. I seems to
be reporting stdout fine, but stderr seems to be lost. My code looks like:

/* open the child process */
child_process = spopen (cmd);
if (child_process == NULL) {
printf ("Could not open pipe: %s\n", cmd);
exit (STATE_UNKNOWN);
}

/* open the child process stderr */
child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
if (child_stderr == NULL) {
printf ("Could not open stderr for %s\n", cmd);
}

/* get results from remote command */
while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process))
asprintf (&result_text, "%s%s", result_text, input_buffer);

/* WARNING if output found on stderr */
if (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
printf ("STDERR: %s\n", input_buffer);
return STATE_WARNING;
}

/* close child stderr */
(void) fclose (child_stderr);

/* close child */
result = spclose (child_process);

cmd contains the correct command to run. When I run it from the command
line, there's a bunch of output to stderr, such that:
$ cmd_myprog > /tmp/out 2> /tmp/err
^C
$ wc -l /tmp/err /tmp/out
4 /tmp/err
0 /tmp/out
4 total
$

So, stderr is getting the output, but stdout gets nothing. When I run this
from my plugin using spopen, I get:
$ ./check_myprog
CRITICAL - Plugin timed out after 15 seconds
$

What I don't understand is, shouldn't the code above output the information
from STDERR of the spopen'ed program? In particular, shouldn't
child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
if (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
printf ("STDERR: %s\n", input_buffer);
return STATE_WARNING;
}
print out the same lines of code that went into /tmp/err in my commandline
execution? Or have I misunderstood the purpose of spopen()?

thanks
dave







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Original poster: [email protected]