I had to do a dirty Linux hack for somebody so they could start a printer with the `cupsenable printername` shell command while being a non-root user. I didn't want them to be able to use the entirety of the `cupsenable` syntax as root, so I just wrote a C wrapper that sanitizes the input in `argv[1]` and calls `system("cupsenable sanitizedprintername")`. I made the program setuid root, but even so, `cupsenable` failed with "permission denied". Then I inserted a `setuid(0)` call before `system()` and, lo and behold, it worked. Disregard the issue of there being a better way to give users control of the printer. There probably is a better way. What I'm interested in are the intricacies of `chmod u+s` vs. `setuid(0)` vs. `system()`. Why did it behave that way?