Get Linux System Last Boot Time - php

Question

From a PHP script I need to get the last system boot time, preferably in the UNIX time stamp format.
Are there any files that are created or modified at boot time? I could read the modified time of the file.
The system type is CentOS.

Answer 1

/proc/uptime
This file contains two numbers: the uptime of the system (seconds), and the amount of time spent in idle process (seconds).
<?php
function get_boottime() {
$tmp = explode(' ', file_get_contents('/proc/uptime'));
return time() - intval($tmp[0]);
}
echo get_boottime() . "\n";

Answer 2

Try this:
Method 1
<?php
$uptime = trim( shell_exec( 'uptime' ) );
// output is 04:47:32 up 187 days, 5:03, 1 user, load average: 0.55, 0.55, 0.54
$uptime = explode( ',', $uptime );
$uptime = explode( ' ', $uptime[0] );
$uptime = $uptime[2] . ' ' . $uptime[3]; // 187 days
?>
Method 2
<?php
$uptime = trim( file_get_contents( '/proc/uptime' ) );
$uptime = explode( ' ', $uptime[0] );
echo $uptime[0];//uptime in seconds
?>
Hope it helps.

Answer 3

who -b # in command-line
Gives you the last boot time (http://www.kernelhardware.org/find-last-reboot-time-and-date-on-linux/)
exec ( $command , $output ); // in PHP
Executes a shell command
strtotime(); // in PHP
Parse about any English textual datetime description into a Unix timestamp
So this will give you the Linux System last boot time :
// in PHP
exec('who -b',$bootTime);//where $bootTime is an array, each line returned by the command is an element of the array
$result = strtotime($bootTime[1]);