On 8 Dec 2020 11:05 -0800, from lm(a)mcvoy.com (Larry McVoy): I don't know if it is implemented that way, but if you have cron, then I suspect you could implement some form of at with even a pretty simple shell script that runs once a minute (via cron) to parse a set of files to see what should be run now as opposed to later. If you have at but not cron, then implementing the other doesn't seem quite as straightforward. It would certainly still be possible, but it would definitely give rise to the question of "wouldn't it be real nice if I could set this task up to run on a recurring basis?" followed by "wouldn't it make more sense for the run-stuff-at-some-time task to run from the recurring-execution tool, than the other way around?". Certainly the step from cron to at seems fairly obvious; not all tasks that are to be executed at some point in time lend themselves well to a recurring nature. Sometimes you really want to do something just once, just not right now. -- Michael Kjörling • https://michael.kjorling.se • michael(a)kjorling.se “Remember when, on the Internet, nobody cared that you were a dog?”

Correct. at was a v7-ism. Trying to put a nicer face on the idea - that is to say, I looked at the "at" command as a user-mode (command) front-end to cron so you didn't have to edit the crontab yourself. The later had been around as a system support idea, since at least 6th edition - maybe 5th. On Tue, Dec 8, 2020 at 1:51 PM Mary Ann Horton <mah(a)mhorton.net> wrote: