用php执行awk linux命令

Question

i want to execute a awk linux command with php , the command is

 mpstat | awk '$12 ~ /[0-9.]+/ { print 100 - $12 }'

i eexcute it wiht linux it works , its gave me the cpu usage in presentage, i try this in php:

$cmd= system("mpstat | awk '$12 ~ /[0-9.]+/ { print 100 - $12 }'",$retval);
echo $retval;

and

$cmd= passthru(" mpstat | awk '$12 ~ /[0-9.]+/ { print 100 - $12 }'",$retval);
 echo $retval;

its not working , i do some searches about it so i put the awk command in variable then execute it :

$var='$12 ~ /[0-9.]+/ { print 100 - $12 }';
$cmd=  exec('mpstat | awk"$var"',$retval);
echo $retval;

and the output is always Array

Answer 1

I wrote a short program to illustrate the difference:

<?php
$cmd = system("ls", $retval);
echo "Cmd: " . $cmd . "\n";
echo "Retval: " . $retval . "\n";
?>

output:

prog.php
Cmd: prog.php
Retval: 0

Answer 2

I normally use popen for these purposes.

Example:

$handle = popen('mpstat | awk \'$12 ~ /[0-9.]+/ { print 100 - $12 }\' 2>&1', 'r');
$read = fread($handle, 8192);
var_dump($read);
pclose($handle);