<?php
$cat = 'mem';

$meminfo_file = '/proc/meminfo';
$meminfo_content = file($meminfo_file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$meminfo_metrics = array(
    'MemTotal' => 'memtotal',
    'MemFree' => 'memfree',
    'Buffers' => 'buffers',
    'Cached' => 'cached',
    'SwapCached' => 'swapcached',
    'SwapTotal' => 'swaptotal',
    'SwapFree' => 'swapfree',
    'Dirty' => 'dirty',
    'Slab' => 'slab',
);
$meminfo_o = array();

foreach ($meminfo_content as $m) {
    $value = array();
    foreach ($meminfo_metrics as $metric => $name) {
        if (preg_match("/^$metric:\s+(\d+) .*/", $m, $value)) {
            $meminfo_o["$cat.$name"] = $value[1];
            break;
        }
    }
}

var_dump($meminfo_o);
?>