Something

$cmds = array(    // this proves that the basic call works    'ssh martin@localhost echo Hallo',    // this does not hang    'ssh martin@localhost tar cf /tmp/try.tgz /root/no/files',    // this hangs here!    'ssh martin@localhost tar cf /tmp/try.tgz /root',    );foreach ($cmds as $cmd) {    echo "\nCMD:".$cmd; flush();    echo "\nPASSTHRU output:\n";    passthru($cmd);    echo "\n\nPROC_OPEN started...\n"; flush();    $p = proc_open($cmd,                   array(0=>array('pipe','r'), 1=>array('pipe','w'), 2=>array('pipe','w')),                   $pipes);    echo "\nSTDOUT output:\n".stream_get_contents($pipes[1]);    echo "\nSTDERR output:\n".stream_get_contents($pipes[2])."--------------\n\n\n";}