屏幕输出到PHP

Question

I have a PHP file with shell commands running through a screen, the commands run fine but I was wondering if there was a way to get this to output to PHP without writing to another file and reading it on PHP's end.

PHP - trace() is just a fancy print_r()

$cmd = 'ls -h /';
trace(shell_exec('screen -S output -p 0 -X stuff "`echo '.$cmd.'\'
\'`"'));

Web output

NULL

Screen output

www-data@:/home/ubuntu$ ls -h /
bin   build  etc   initrd.img      lib         media  opt   root  selinux  sys  usr  vmlinuz
boot  dev    home  initrd.img.old  lost+found  mnt    proc  sbin  srv      tmp  var  vmlinuz.old

Any suggestions?

--Edit--

Certain commands aren't outputting directly, one of the reasons I'm using screen

PHP

$cmd = 's3ls';
trace(shell_exec('screen -S output -p 0 -X stuff "`echo '.$cmd.'\'
\'`"'));
trace(shell_exec($cmd));

Web output

trace:NULL
trace:NULL

Screen

www-data@:/home/ubuntu$ s3ls
+---------------+--------------------------+
|     Name      |       CreationDate       |
+---------------+--------------------------+
| bucket        | 2012-05-31T13:08:51.000Z |
| bucket        | 2012-01-17T16:51:58.000Z |
| bucket        | 2012-03-31T11:19:54.000Z |
+---------------+--------------------------+

Answer 1

void passthru ( string $command [, int &$return_var ] )

The passthru() function is similar to the exec() function in that it executes a command. This function should be used in place of exec() or system() when the output from the Unix command is binary data which needs to be passed directly back to the browser. A common use for this is to execute something like the pbmplus utilities that can output an image stream directly. By setting the Content-type to image/gif and then calling a pbmplus program to output a gif, you can create PHP scripts that output images directly.

Though apparently it may be a bit flaky.