NAME
atd - ’at’ script daemon

SYNOPSIS
atd

DESCRIPTION
Atd is the ’at’ script daemon started by the system at boot time to
run shell scripts queued for execution by at(1).

Atd reads the spool directory, then examines it once a minute to
see if it has changed. Only if the directory has changed is it
re-read.

The file name indicates the type of script, it’s start time, and
it’s periodicity:

/usr/spool/at/yy.ddd.hhmm[hdwmbB.]nn

yy, ddd, hhmm :- year, day, hour and minute.
h, d, w, m, b :- hourly, daily, weekly, monthly and boot.
B :- batch script.
’.’ :- once only script.
nn :- unique number for given yy.ddd.hhmm.

When a script is due to be executed, a shell is forked with the
script as standard input and the user ID is set to that of the
owner. The script file is removed prior to execution (unless a
periodic script, in which case the file is left unchanged).
Standard output is directed to /dev/null. Any error output is
captured and sent to the user via mail(1).

FILES
/usr/spool/at ’at’ script spool area
yy.ddd.hhmm.* script to be executed at year yy, day ddd,
and time hhmm.

SEE ALSO
at(1), atq(1), atrm(1).

DIAGNOSTICS
Diagnostics are written to the standard error for compatibility
with nanny(8).