at(1)
NAME
at − execute commands at a later time
SYNTAX
at time [ day ] [ file ]
DESCRIPTION
The at command uses a copy of the named file (standard input default) as input to sh(1) at a specified later time. A cd 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 IDs 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 letters follow the digits, a 24 hour clock time is understood.
The optional day is either a month name followed by a day number, or a day of the week. If the word “week” follows, invocation is moved seven days further off. Names of months and days may be recognizably truncated. Examples of legitimate commands are:
at 8am jan 24
at 1530 fr week
The at programs are executed by periodic execution of the command /usr/lib/atrun from cron(8).
RESTRICTIONS
Standard output or error output is lost unless redirected.
The exact time that your file is executed actually depends on when the cron command invokes /usr/lib/atrun. Therefore, your file may not be executed at the exact time that you specified.
Because of scheduling irregularities, you should not schedule your files to be executed 24 hours into the future.
FILES
/usr/spool/at/yy.ddd.hhhh.uu
Activity to be performed at hour hhhh of 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/atrunProgram that executes activities that are due
pwd(1)