% at options time < scriptfile 

This submits scriptfile for execution at a later time. The redirection (<) isn't required on versions that can read directly from a file. By default, at reads the commands from its standard input. So if you don't want to write a script, you can omit the file and type your commands on the terminal, terminated by CTRL-d:

% at  options time

Command 1
Command 2
...
CTRL-d

The time is most commonly a four-digit number representing a time on a 24-hour clock. For example, 0130 represents 1:30 a.m. and 1400 represents 2 p.m. You can also use abbreviations such as 1am, 130pm, and so on.

-- ML

25.4. Including Standard Input Within a cron Entry		25.6. Making Your at Jobs Quiet