Add execInDir function

php/includes/functions.php

@@ -16,4 +16,9 @@ function line(string $line): void
 {
     line($line);
     exit($code);
-}
+}
+
+function execInDirectory(string $dir, string $command): ?string
+{
+    return shell_exec(sprintf('cd %s && %s', $dir, $command));
+}