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## Auto-converted by kwiki2moinmoin v2005-10-07
'''cron''', '''at''' and '''anacron''' are system processes used for periodic command execution.
#language en
~-[[DebianWiki/EditorGuide#translation|Translation(s)]]: English - [[it/CronAnacronAtBatchSchedulers|Italiano]] - [[ru/CronAnacronAtBatchSchedulers|Русский]]-~
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'''cron''' and '''at''' differ in one respect. '''cron''' is based on an absolute timetable whereas '''at''' is relative. For example, a '''cron''' entry would execute a command every Thursday in February. An '''at''' entry would run a specific command exactly 23 hours and 17 minutes from now. DebPkg:cron, DebPkg:anacron and DebPkg:at are system processes used for periodic command execution.
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'''It's also worth mentioning DebianPackage:anacron here, as well.''' '''anacron''' allows tasks to be scheduled and performed when the system is not running 24 hours a day, 7 days a week. cron and at differ in one respect. cron is based on an absolute timetable whereas at is relative. For example, a cron entry would execute a command every Thursday in February. An at entry would run a specific command exactly 23 hours and 17 minutes from now.
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Debian comes with several housekeeping '''cron''' entries enabled by default. Each of these entries may be viewed by logging in as the appropriate user (likely root) and running the '''crontab''' command.
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Any user may view the system's scheduled tasks by looking at the /etc/crontab file: <<TableOfContents(2)>>
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$ cat /etc/crontab = cron =
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Debian does not come with any '''at''' entries enabled on a standard installation. To view any '''at''' entries that you have submitted, use the '''atq''' command. Debian comes with several housekeeping cron entries enabled by default. Each of these entries may be viewed by logging in as the appropriate user (likely root) and running the {{{crontab}}} command.

Any user may view the __system__'s scheduled tasks by looking at the files {{{/etc/crontab}}} and {{{/etc/cron.*/}}}

See:
 * [[DebianMan:1/crontab|crontab(1)]] - tool to maintain crontab files for individual users
 * [[DebianMan:5/crontab|crontab(5)]] - syntax of tables for driving cron

= anacron =

It's also worth mentioning anacron here, as well. anacron allows tasks to be scheduled and performed when the system is not running 24 hours a day, 7 days a week (It's installed by default by Debian-Installer on laptops, and with the desktops task).

Any user may view the system's scheduled tasks by looking at the {{{/etc/anacrontab }}}file:
{{{
 $ cat /etc/anacrontab
}}}

See:
 * [[DebianMan:5/anacrontab|anacrontab(5)]] - configuration file for anacron
 * [[DebianMan:8/anacron|anacron(8)]] - runs commands periodically

= at =
{{{at}}} (and {{{batch}}}) execute a command at a later time (once). Debian does not come with any at entries enabled on a standard installation.

To view any at entries that you have submitted, use the {{{atq}}} command.

See:
 * [[DebianMan:1/at|at(1)]] - manpage
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Translation(s): English - Italiano - Русский

cron, anacron and at are system processes used for periodic command execution.

cron and at differ in one respect. cron is based on an absolute timetable whereas at is relative. For example, a cron entry would execute a command every Thursday in February. An at entry would run a specific command exactly 23 hours and 17 minutes from now.

Contents

  1. cron
  2. anacron
  3. at

cron

Debian comes with several housekeeping cron entries enabled by default. Each of these entries may be viewed by logging in as the appropriate user (likely root) and running the crontab command.

Any user may view the system's scheduled tasks by looking at the files /etc/crontab and /etc/cron.*/

See:

  • crontab(1) - tool to maintain crontab files for individual users

  • crontab(5) - syntax of tables for driving cron

anacron

It's also worth mentioning anacron here, as well. anacron allows tasks to be scheduled and performed when the system is not running 24 hours a day, 7 days a week (It's installed by default by Debian-Installer on laptops, and with the desktops task).

Any user may view the system's scheduled tasks by looking at the /etc/anacrontab file:

 $ cat /etc/anacrontab

See:

at

at (and batch) execute a command at a later time (once). Debian does not come with any at entries enabled on a standard installation.

To view any at entries that you have submitted, use the atq command.

See: