Printing out one line to screen from popen in PHP? - php

Question

I'm making a batch megadownload site in PHP. I'm parsing the input, validating it, then passing it to a bash script. I'm piping the output to the web page, but the contents of the webpage show like this.
8lX0JsBi.part01.rar: 0.00% - 0 bytes of 1000.0?MiB
8lX0JsBi.part01.rar: 0.09% - 917.7?KiB (939752 bytes) of 1000.0?MiB (916.7?KiB/s)
8lX0JsBi.part01.rar: 0.63% - 6.3?MiB (6566240 bytes) of 1000.0?MiB (5.3?MiB/s)
8lX0JsBi.part01.rar: 1.38% - 13.8?MiB (14430560 bytes) of 1000.0?MiB (7.0?MiB/s)
8lX0JsBi.part01.rar: 2.30% - 23.0?MiB (24129888 bytes) of 1000.0?MiB (9.0?MiB/s)
I'd like it to only show one line at a time that updates a single line.
8lX0JsBi.part01.rar: 2.30% - 23.0?MiB (24129888 bytes) of 1000.0?MiB (9.0?MiB/s)
Here is the function I'm using to pipe stdout to the webpage.
<?php
/**
* Execute the given command by displaying console output live to the user.
* #param string cmd : command to be executed
* #return array exit_status : exit status of the executed command
* output : console output of the executed command
*/
function liveExecuteCommand($cmd)
{
while (# ob_end_flush()); // end all output buffers if any
$proc = popen("$cmd 2>&1 ; echo Exit status : $?", 'r');
$live_output = "";
$complete_output = "";
while (!feof($proc))
{
$live_output = fread($proc, 4096);
$complete_output = $complete_output . $live_output;
echo "$live_output";
# flush();
}
pclose($proc);
// get exit status
preg_match('/[0-9]+$/', $complete_output, $matches);
// return exit status and intended output
return array (
'exit_status' => intval($matches[0]),
'output' => str_replace("Exit status : " . $matches[0], '', $complete_output)
);
}
?>

Answer 1

You have a few options:
Using clear, though this will clear the entire console.
system('clear');
echo '5%';
sleep(5);
system('clear');
echo '10%';
Or using /r, This will replace the last printed out line.
echo "5%";
sleep(5);
echo "\r10%";
You can also user cursor manipulation and character counting or the output buffer. But I think that will be a bit much for this.