Magic number (Re: cost of popen())

[Shigio YAMAGUCHI]

Reading your code, I have understood that xargs(1) is not used.
By the way, I cannot understand the folloging code:

                path_list_max = ARG_MAX;
                path_list_max -= 2048;
                if (path_list_max > 20 * 1024)
                        path_list_max = 20 * 1024;
                path_list_max -= env_size();
                path_list_max -= strbuf_getlen(sb);
                path_list_max -= 40;                            <= (*)
                if (path_list_max < 0)
                        path_list_max = 0;

What is the 40?
--
Shigio YAMAGUCHI <address@hidden> - Tama Communications Corporation
PGP fingerprint: D1CB 0B89 B346 4AB6 5663  C4B6 3CA5 BBB3 57BE DDA3