Proper shell execution in PHP

Question

The problem

I was using a function that made use of proc_open() to invoke shell commands. It seems the way I was doing STDIO was wrong and sometimes cause

Answer 1

The whole problem with hanging in stream_get_contents is in the way how process is created. The correct way is to open STDOUT with read/write mode of pipe, eg:

$descriptor = array (0 => array ("pipe", "r"), 1 => array ("pipe", "rw"), 2 => array ("pipe", "rw"));
//Open the resource to execute $command
$t->pref = proc_open($command,$descriptor,$t->pipes);
//Set STDOUT and STDERR to non-blocking 
stream_set_blocking ($t->pipes[0], 0);
stream_set_blocking ($t->pipes[1], 0);

This is obvious that when stream_get_contents wants to read the STDOUT pipe it needs read mode. The same bug with hang/freeze/block is in this nice class https://gist.github.com/Arbow/982320

Then blocking disappears. But read does not read nothing.