Composer/ScriptHandler.php
public static function createSymlink($symlinkTarget, $symlinkName)
    {
        if (false === @symlink($symlinkTarget, $symlinkName)) {
            throw new \UnexpectedValueException("An error occurred while creating symlink '{$symlinkName}'");
        }
        if (false === $target = readlink($symlinkName)) {
            throw new \UnexpectedValueException("Symlink {$symlinkName} points to target {$target}");
        }
    }
public static function createSymlink($symlinkTarget, $symlinkName)
    {
        if (false === @symlink($symlinkTarget, $symlinkName)) {
            throw new \UnexpectedValueException("An error occurred while creating symlink '{$symlinkName}'");
        }
        if (false === $target = readlink($symlinkName)) {
            throw new \UnexpectedValueException("Symlink {$symlinkName} points to target {$target}");
        }
    }
Create the symlink.

@param string $symlinkTarget The Target
@param string $symlinkName   The Name

@throws \Exception