In addition to the last post (13 years ago) from Dennis K. I corrected two typos (constant SSH2_STREAM_STDIO was misspellt) and removed (too many) brackets - this code works:

<?php
      $stdout_stream = ssh2_exec($connection, "lsssss -la");

      $sio_stream = ssh2_fetch_stream($stdout_stream, SSH2_STREAM_STDIO);
      $err_stream = ssh2_fetch_stream($stdout_stream, SSH2_STREAM_STDERR);
      
      stream_set_blocking($sio_stream, true);
      stream_set_blocking($err_stream, true);
      
      $result_dio = stream_get_contents($sio_stream);
      $result_err = stream_get_contents($err_stream);

      echo 'stderr: ' . $result_err;
      echo 'stdio : ' . $result_dio;
?>

In addition to the last post from Ricardo Striquer:

Simple block the stream with stream_set_blocking(), and you dont have to sleep() the script...

<?php
stdout_stream = ssh2_exec($connection, "/bin/lssss -la /tmp");

$err_stream = ssh2_fetch_stream($stdout_stream, SSH2_STREAM_STDERR);

$dio_stream = ssh2_fetch_stream($stdout_stream, SSH2_STREAM_STDDIO);

stream_set_blocking($err_stream, true);
stream_set_blocking($dio_stream, true);

$result_err = stream_get_contents($err_stream));
$result_dio = stream_get_contents($dio_stream));
?>

I got a friend using those functions and he was not able to use this ssh2_fetch_stream function. First of all I got the ssh2_shell sample by webmaster at spectreanime dot com, but this function does not work with his sample, i believe thats because he use fwrite instead of ssh2_shell or ssh2_exec to run the command.

This sample below is to run under a command line and is fully functional. note that i add the sleep as advised by webmaster at spectreanime dot com

<?php
echo "Connexion SSH ";
if (!($connection=@ssh2_connect("69.69.69.69", 22))) {
   echo "[FAILED]\n";
   exit(1);
}
echo "[OK]\nAuthentification ";

if (!@ssh2_auth_password($connection,"root","YourPassword")) {
   echo "[FAILED]\n";
   exit(1);
}
echo "[OK]\n";

$stdout_stream = ssh2_exec($connection, "/bin/lssss -la /tmp");
sleep(1);
$stderr_stream = ssh2_fetch_stream($stdout_stream, SSH2_STREAM_STDERR);

echo "Erros encontrados!\n------------\n";
while($line = fgets($stderr_stream)) { flush(); echo $line."\n"; }
echo "------------\n";

while($line = fgets($stdout_stream)) { flush(); echo $line."\n";}

fclose($stdout_stream);
?>

I successfully used fgets in PHP4

examples

<?php
$stderr = fgets(ssh2_fetch_stream($channel, SSH2_STREAM_STDERR), 8192);

$str = fgets(ssh2_fetch_stream($channel, SSH2_STREAM_STDIO), 8192);
?>