Qualcuno potrebbe fornire alcuni esempi di utilizzo per il comando at ? Sto trovando il man super confusion.
$ man at
Ad esempio, se volessimo eseguire un comando tra 10 minuti, è possibile farlo utilizzando at ? (e senza usare sleep )
Le specifiche del tempo per "10 minuti da ora" sono now +10 minutes . Ad esempio,
echo 'open ~' | at now +10 minutes
Tuttavia, il sistema at è disabilitato di default in macOS, come menzionato nella pagina man at :
IMPLEMENTATION NOTES
Note that at is implemented through the launchd(8) daemon periodically
invoking atrun(8), which is disabled by default. See atrun(8) for infor-
mation about enabling atrun.
La pagina man di atrun dice che è necessario eseguire
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.atrun.plist
I Use the
atcommand when I need to do some heavy processing on data, which I want to have executed during the night, when I am not behind my computer. Of course I could start the process just after I leave, but this is something I tend to forget.The result of the command is not different from regularly execution of the script or command.
@Bernhard
Che cosa fa
estratto da at man page
NAME
at, batch, atq, atrm - queue, examine or delete jobs for later execution
DESCRIPTION
at and batch read commands from standard input or a specified file
which are to be executed at a later time, using /bin/sh.
Utilizzo
L'uso degli strumenti:
Usage: at [-V] [-q x] [-f file] [-mldbv] timespec ...
at [-V] [-q x] [-f file] [-mldbv] -t time
at -c job ...
atq [-V] [-q x]
atrm [-V] job ...
batch at include 4 comandi ( at , atq , atrm e batch ). Usa at e batch per pianificare i lavori, atq per vedere cosa è programmato e atrm per rimuovere un lavoro prima che funzioni.
$ at -f <cmd> timspec
timespec
Il tempo di eseguire il lavoro at può essere specificato in diversi modi.
modulo estratto nella pagina man
At allows fairly complex time specifications, extending the POSIX.2 standard. It accepts times of the form HH:MM to run a job at a specific time of day. (If that time is already past, the next day is assumed.) You may also specify mid‐ night, noon, or teatime (4pm) and you can have a time-of-day suffixed with AM or PM for running in the morning or the evening. You can also say what day the job will be run, by giving a date in the form month-name day with an optional year, or giving a date of the form MMDD[CC]YY, MM/DD/[CC]YY, DD.MM.[CC]YY or [CC]YY-MM-DD. The specification of a date must follow the specification of the time of day. You can also give times like now + count time-units, where the time- units can be minutes, hours, days, or weeks and you can tell at to run the job today by suffixing the time with today and to run the job tomorrow by suffixing the time with tomorrow.
Esempi
Supponi di avere questo script di shell.
$ cat mycrontest.sh
#!/bin/bash
echo "It is now $(date +%T) on $(date +%A)"
Esecuzione campione:
$ ./mycrontest.sh
It is now 18:37:42 on Friday
Esempio di invio di lavoro:
$ at -f mycrontest.sh 10pm tomorrow
job 14 at Sun Jul 8 22:00:00 2007
$ at -f mycrontest.sh 2:00 tuesday
job 15 at Tue Jul 10 02:00:00 2007
$ at -f mycrontest.sh 2:00 july 11
job 16 at Wed Jul 11 02:00:00 2007
$ at -f mycrontest.sh 2:00 next week
job 17 at Sat Jul 14 02:00:00 2007Crediti a @slm
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