PHP Code should use DIRECTORY_SEPARATOR
Instead, the variable "fs_div" and constant "FS_DIV" are used:
root@ispconfig:/usr-local-ispconfig# grep -ri fs_div .
./server/server.php:if(is_file(:$conf['fs_div'] = '/'; // File system separator (divider), "\" on Windows and "/" on Linux and UNIX
./interface/lib/config.inc.php~:$conf['classpath'] = conf['temppath'].
conf['fs_div'].'.ispconfig_lock')){
./server/server.php: if(is_file(conf['temppath'].
conf['fs_div'].'.ispconfig_lock')){
./server/server.php:@touch(conf['temppath'].
conf['fs_div'].'.ispconfig_lock');
./server/server.php:$app->log('Set Lock: '.conf['temppath'].
conf['fs_div'].'.ispconfig_lock', LOGLEVEL_DEBUG);
./server/server.php:@unlink($conf['temppath'].$conf['fs_div'].'.ispconfig_lock');
./server/server.php:$app->log('Remove Lock: '.$conf['temppath'].$conf['fs_div'].'.ispconfig_lock',LOGLEVEL_DEBUG);
./server/lib/classes/modules.inc.php: $modules_dir = conf['rootpath'].
conf['fs_div'].subPath.
conf['fs_div'];
./server/lib/classes/plugins.inc.php: $plugins_dir = conf['rootpath'].
conf['fs_div'].subPath.
conf['fs_div'];
./server/lib/config.inc.php:$conf['fs_div'] = '/'; // File system separator, "\" on Windows and "/" on Linux and UNIX
./server/lib/config.inc.php:$conf['classpath'] = conf['rootpath'].
conf['fs_div'].'lib'.$conf['fs_div'].'classes';
./server/lib/config.inc.php:$conf['temppath'] = conf['rootpath'].
conf['fs_div'].'temp';
./server/lib/config.inc.php:define('FS_DIV',$conf['fs_div']);
./server/lib/config.inc.php:define('INCLUDE_ROOT',SERVER_ROOT.FS_DIV.'lib');
./server/lib/config.inc.php:define('CLASSES_ROOT',INCLUDE_ROOT.FS_DIV.'classes');
./server/lib/config.inc.php:$conf['log_file'] = conf['ispconfig_log_dir'].
conf['fs_div'].'ispconfig.log';
./interface/lib/config.inc.phpconf['rootpath'].
conf['fs_div'].'lib'.$conf['fs_div'].'classes';
./interface/lib/config.inc.php~:$conf['temppath'] = conf['rootpath'].
conf['fs_div'].'temp';
./interface/lib/config.inc.php~:define('FS_DIV',$conf['fs_div']);
./interface/lib/config.inc.php~:define('INCLUDE_ROOT',SERVER_ROOT.FS_DIV.'lib');
./interface/lib/config.inc.php~:define('CLASSES_ROOT',INCLUDE_ROOT.FS_DIV.'classes');
./interface/lib/classes/plugin.inc.php: $plugins_dir = ISPC_LIB_PATH.FS_DIV.'plugins'.FS_DIV;
./interface/lib/classes/plugin.inc.php: plugin_file = ISPC_LIB_PATH.FS_DIV.'plugins'.FS_DIV.
plugin_name.'.inc.php';
./interface/lib/config.inc.php:$conf['fs_div'] = '/'; // File system separator, "\" on Windows and "/" on Linux and UNIX
./interface/lib/config.inc.php:$conf['classpath'] = conf['rootpath'].
conf['fs_div'].'lib'.$conf['fs_div'].'classes';
./interface/lib/config.inc.php:$conf['temppath'] = conf['rootpath'].
conf['fs_div'].'temp';
./interface/lib/config.inc.php:define('FS_DIV',$conf['fs_div']);
./interface/lib/config.inc.php:define('INCLUDE_ROOT',SERVER_ROOT.FS_DIV.'lib');
./interface/lib/config.inc.php:define('CLASSES_ROOT',INCLUDE_ROOT.FS_DIV.'classes');
./interface/lib/config.inc.php:$conf['log_file'] = conf['ispconfig_log_dir'].
conf['fs_div'].'ispconfig.log';
root@ispconfig:~/usr-local-ispconfig#