Using cron

  • The cron facility consists of crond, the cron daemon, and crontab files containing job-scheduling information.

  • cron is intended for the execution of commands on a periodic basis.

  • crond examines all crontab files every minute.

  • Each system user has access to cron through a personal crontab file.

  • The crontab command allows the crontab file to be viewed and, with the –e option, edited.

  • Entries in the crontab file are in the form of:

    minute hour day month dayofweek command
  • Asterisks in any of the time fields match all possible values.

  • In addition to personal crontab files, the system has its own crontab files in /etc/crontab, as well as files in /etc/cron.d.

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