at files and permissions

[Bob Wilber]

Brandon S. Allbery writes:
>at needs root permissions so it can setuid() itself to the owner of the at
>job file, so it can execute the job as the user who submitted it.

No.  "at" doesn't execute the job file, "atrun" does.  (Or, on some systems,
cron itself.)  "at" only needs the ability to create a file in the at spool
directory.  As I stated in my previous post, this shouldn't require root
capabilities, but on System V, a bug in the setuid(2) command forces "at"
to be run setuid to root.

Bob Wilber