Provided by: at_3.2.5-1ubuntu1_amd64 
      
    
NAME
       at.allow, at.deny - determine who can submit jobs via at or batch
DESCRIPTION
       The /etc/at.allow and /etc/at.deny files determine which user can submit commands for later execution via
       at(1) or batch(1).
       The format of the files is a list of usernames, one on each line.  Whitespace is not permitted.
       If the file /etc/at.allow exists, only usernames mentioned in it are allowed to use at.
       If  /etc/at.allow  does  not  exist,  /etc/at.deny is checked, every username not mentioned in it is then
       allowed to use at.
       An empty /etc/at.deny means that every user may use at.
       If neither exists, only the superuser is allowed to use at.
SEE ALSO
       at(1), cron(8), crontab(1), atd(8).
                                                    Sep 1997                                         AT.ALLOW(5)