at command

[jld9]

How do I set my system up so that only the root and my usera can use the at command?

[RobinVossen]

you mean command line?
Change to .bashrc file to check the userid to be 1.
Make it only editable to chance it if you are root.

Hope that helps.

[anomie]

From the at(1) manpages:

... permission to use at is determined by the files /var/at/at.allow and
/var/at/at.deny.

If the file /var/at/at.allow exists, only usernames mentioned in it are
allowed to use at. In these two files, a user is considered to be listed
only if the user name has no blank or other characters before it on its
line and a newline character immediately after the name, even at the end
of the file. Other lines are ignored and may be used for comments.

If /var/at/at.allow does not exist, /var/at/at.deny is checked, every
username not mentioned in it is then allowed to use at.

If neither exists, only the superuser is allowed use of at. This is the
default configuration.

This from my FBSD 6.2 box. Check your manpages for particulars (especially default config behavior and file locations).