Storing Results of System Command in a Variable

SurgeProto

OK, I've been banging my head against a wall here for several hours and can't seem to find a solution. Basically, I need to run a system command through PHP (I've tested using exec, system, passthru, etc.) and store the output to a variable. I'm running a sox command to get the stats of a sound file which returns output like the following:

Samples read:             27600
Length (seconds):      3.450000
Scaled by:         2147483647.0
Maximum amplitude:     0.171753
Minimum amplitude:    -0.171753
Midline amplitude:     0.000000
Mean    norm:          0.003991
Mean    amplitude:    -0.000039
RMS     amplitude:     0.013365
Maximum delta:         0.175537
Minimum delta:         0.000000
Mean    delta:         0.002996
RMS     delta:         0.009204
Rough   frequency:          876
Volume adjustment:        5.822

I need all of this output trapped in a variable so I can parse the length, but none of these functions seem to do this. I've read all the documentation and even the comments. Any insight on how to accomplish this would be tremendously appreciated!!

laserlight

[man]exec/man is what you are looking for. The output would be in an array as provided by the optional second parameter.

NogDog

$resultString = shell_exec('system command');

Note however that there are all sorts of "gotchas" when using these [man]exec[/man] type functions, mainly due to various security setting options in PHP.

SurgeProto

I've tried the following exec code:

$command = "sox /tmp/file.wav -e stat";
$test = exec($command,$output,$return_var);
echo "\n\n";
var_dump($test);
echo "\n\n";
var_dump($output);
echo "\n\n";
var_dump($return_var);

and this is the response I get:

string(0) ""


array(0) {
}


int(0)

SurgeProto

$output = shell_exec($command);
echo "\n\n";
var_dump($output);

is returning NULL

am I doing something wrong in the code?

NogDog

What do you get if you run this?

<?php
echo ini_get('safe_mode');

If that's not an issue, also remember that a PHP web page will be executed by the webserver user (at least in most installations), so it may not have the same permissions and environment settings as your personal login account. One common issue is the path setting, which may require you to provide the full path to the executable to be run, e.g.: [FONT="Courier New"]"/usr/bin/sox /tmp/file.wav -e stat"[/FONT] (changing [FONT="Courier New"]"/usr/bin/"[/FONT] to whatever the actual path is).

SurgeProto

No, it's not running in safe mode. I was able to solve my problem using the following code. I thought I'd paste it in case anyone else may be looking for a similar solution.

$command = "sox /tmp/recording.wav -e stat";						$sox_stats = array();
$output = exec($command . ' 2>&1', $sox_stats, $return);

$sox_stats is an array that contains all the output.

laserlight

Sigh, I suspected as much. It is strange that normal output is sent to stderr instead of stdout though.