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run a cron job only once - sometimes crons is just too much to do what you want to accomplish. you might simply want to run a single command at a specified [990], Last Updated: Mon Jun 24, 2024
Downther
Sat Feb 27, 2010
2 Comments
804 Visits
Well, today I was making some cron jobs, and I realized I wanted to schedule this script but I only wanted to do It once and that was It
but It seems with cron jobs, It cycles depending on what Intervals you set It.
well, If you are In the same situation as I am, you can use the
atsometimes crons Is just too much to do what you want to accomplish. you might simply want to run a single command at a specified point In the future on a one time basis, rather than on on going basis, for this takes, Linux provides another command, Its call: at
in ordinary use this command takes silge opti
for example
at -f mycommands.txt noon
this will run at noon time
NAME at, batch, atq, atrm - queue, examine or delete jobs for later execution SYNOPSIS at [-V] [-q queue] [-f file] [-mldbv] TIME at [-V] [-q queue] [-f file] [-mldbv] -t time_arg at -c job [job...] atq [-V] [-q queue] atrm [-V] job [job...] batch [-V] [-q queue] [-f file] [-mv] [TIME] DESCRIPTION at and batch read commands from standard input or a specified file which are to be executed at a later time . at executes commands at a specified time. atq lists the userâs pending jobs, unless the user is the superuser; in that case, everybodyâs jobs are listed. The format of the output lines (one for each job) is: Job number, date, hour, job class. atrm deletes jobs, identified by their job number. batch executes commands when system load levels permit; in other words, when the load average drops below 0.8, or the value specified in the invo- cation of atrun. 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 midnight, 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 MMDDYY or MM/DD/YY or DD.MM.YY. 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. For example, to run a job at 4pm three days from now, you would do at 4pm + 3 days, to run a job at 10:00am on July 31, you would do at 10am Jul 31 and to run a job at 1am tomorrow, you would do at 1am tomorrow. The exact definition of the time specification can be found in /usr/share/doc/at-3.1.8/timespec. For both at and batch, commands are read from standard input or the file spec- ified with the -f option and executed. The working directory, the environment (except for the variables TERM, DISPLAY and _) and the umask are retained from the time of invocation. An at - or batch - command invoked from a su(1) shell will retain the current userid. The user will be mailed standard error and standard output from his commands, if any. Mail will be sent using the com- mand /usr/sbin/sendmail. If at is executed from a su(1) shell, the owner of the login shell will receive the mail. The superuser may use these commands in any case. For other users, permission to use at is determined by the files /etc/at.allow and /etc/at.deny. If the file /etc/at.allow exists, only usernames mentioned in it are allowed to use at. If /etc/at.allow does not exist, /etc/at.deny is checked, every username not mentioned in it is then allowed to use at.