function System::which

The "which" command (show the full path of a command)

@author Stig Bakken <ssb@php.net>

Parameters

string $program The command to search for:

mixed $fallback Value to return if $program is not found:

Return value

mixed A string with the full path or false if not found

File

vendor/pear/pear-core-minimal/src/System.php, line 495

Class

System

System offers cross platform compatible system functions

Code

public static function which($program, $fallback = false) {
    // enforce API
    if (!is_string($program) || '' == $program) {
        return $fallback;
    }
    // full path given
    if (basename($program) != $program) {
        $path_elements[] = dirname($program);
        $program = basename($program);
    }
    else {
        $path = getenv('PATH');
        if (!$path) {
            $path = getenv('Path');
            // some OSes are just stupid enough to do this
        }
        $path_elements = explode(PATH_SEPARATOR, $path);
    }
    if (OS_WINDOWS) {
        $exe_suffixes = getenv('PATHEXT') ? explode(PATH_SEPARATOR, getenv('PATHEXT')) : array(
            '.exe',
            '.bat',
            '.cmd',
            '.com',
        );
        // allow passing a command.exe param
        if (strpos($program, '.') !== false) {
            array_unshift($exe_suffixes, '');
        }
    }
    else {
        $exe_suffixes = array(
            '',
        );
    }
    foreach ($exe_suffixes as $suff) {
        foreach ($path_elements as $dir) {
            $file = $dir . DIRECTORY_SEPARATOR . $program . $suff;
            // It's possible to run a .bat on Windows that is_executable
            // would return false for. The is_executable check is meaningless...
            if (OS_WINDOWS) {
                if (file_exists($file)) {
                    return $file;
                }
            }
            else {
                if (is_executable($file)) {
                    return $file;
                }
            }
        }
    }
    return $fallback;
}