AT(1) General Commands Manual AT(1)
at - execute commands at a later time
at time [ day ] [ file ]
At squirrels away a copy of the named file (standard input default) to
be used as input to sh(1) at a specified later time. A cd(1) command
to the current directory is inserted at the beginning, followed by
assignments to all environment variables. When the script is run, it
uses the user and group ID of the creator of the copy file.
The time is 1 to 4 digits, with an optional following `A', `P', `N' or
`M' for AM, PM, noon or midnight. One and two digit numbers are taken
to be hours, three and four digits to be hours and minutes. If no let-
ters follow the digits, a 24 hour clock time is understood.
The optional day is either (1) a month name followed by a day number,
or (2) a day of the week; if the word `week' follows invocation is
moved seven days further off. Names of months and days may be recog-
nizably truncated. Examples of legitimate commands are
at 8am jan 24
at 1530 fr week
At programs are executed by periodic execution of the command
/usr/lib/atrun from cron(8). The granularity of at depends upon how
often atrun is executed.
Standard output or error output is lost unless redirected.
activity to be performed at hour hhhh of year day ddd of year yy. uu
is a unique number.
/usr/spool/at/lasttimedone contains hhhh for last hour of activity.
/usr/spool/at/past directory of activities now in progress
/usr/lib/atrun program that executes activities that are due
Complains about various syntax errors and times out of range.
Due to the granularity of the execution of /usr/lib/atrun, there may be
bugs in scheduling things almost exactly 24 hours into the future.