- * if it is too old, rename it to g<inum>.<pid> (where
- * <inum> and <pid> are in decimal)
- * and run garbage collection
- * - run cgi-fcgi -connect SOCKET SCRIPT
+ * if it is too old, unlink it
+ * - dup2 stderr, mark no cloexec
+ * - run cgi-fcgi -connect SOCKET \
+ * cgi-fcgi-interp --stage2 <was-stderr> <socket> <interp> <script>
+ *
+ * -E<was-stderr> does this:
+ * - dup2 <was-stderr> to fd 2
+ * - open /dev/null and expect fd 1 (and if not, close it)
+ * - become a new process group
+ * - lstat <socket> to find its inum, mtime
+ * - fork/exec <interp> <script>
+ * - periodically lstat <socket> and
+ * if inum, mtime have changed
+ * kill process group (at second iteration)