at -- examine or delete jobs for later execution
at is as specified in ISO POSIX (2003) but with
differences as listed below.
is functionally equivalent to the -r option specified in
ISO POSIX (2003).
need not be supported, but the '-d' option is equivalent.
- -t time
need not be supported.
Optional Control Files
The implementation shall support the XSI optional behavior
for access control; however the files
at.deny may reside in
/etc rather than