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— | dcron [2015/06/01 22:05] (current) – created - external edit 127.0.0.1 | ||
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+ | ====== dcron ====== | ||
+ | * [[http:// | ||
+ | * [[http:// | ||
+ | |||
+ | Since there are a lot of cron daemons available, asking //why use dcron// is a valid question. | ||
+ | |||
+ | * has a homepage, with documentation (see cronie) | ||
+ | * has syntax extensions (@daily) | ||
+ | * can log to a separate file | ||
+ | * can send job output to an external email address directly | ||
+ | * permissions is handled simply by user being in '' | ||
+ | * each user has their own crontab | ||
+ | * better logging | ||
+ | |||
+ | === User Permissions === | ||
+ | |||
+ | Users must belong to the '' | ||
+ | |||
+ | === Logging === | ||
+ | |||
+ | By default, dcron logs all messages less than or equal to log level '' | ||
+ | |||
+ | The log file can be set by ''/ | ||
+ | |||
+ | Unlike cronie, dcron does not send a notice to the system logger that a user's crontab has been edited. | ||
+ | |||
+ | === Log Output === | ||
+ | |||
+ | dcron has better log information sent to the log to help debugging. | ||
+ | |||
+ | < | ||
+ | Oct 23 11:25:01 beandog crond: FILE / | ||
+ | </ | ||
+ | |||
+ | You can see that the log file includes the cron file being run, the user, the PID as well as the actual command. | ||
+ | |||
+ | === Job Duplication === | ||
+ | |||
+ | From the man page: | ||
+ | |||
+ | Cron jobs are not re-executed if a previous instance of them is still running. | ||
+ | |||
+ | === System Clock === | ||
+ | |||
+ | If the system clock changes time, and a cron job should have run, dcron will run it. From the man page: | ||
+ | |||
+ | crond automatically detects when the clock has been changed, during its per-minute scans. | ||
+ | |||
+ | For example, suppose it's 10 am, and a job is scheduled to run every day at 10:30 am. If you set the system' | ||
+ | |||
+ | === dcron Extensions === | ||
+ | |||
+ | Special extensions that dcron supports: | ||
+ | |||
+ | ** Start a job once, when crond starts up ** | ||
+ | |||
+ | < | ||
+ | @reboot run-first.sh | ||
+ | </ | ||
+ | |||
+ | ** Shortcuts ** | ||
+ | |||
+ | You can use @daily, @hourly, etc., but when doing so, the entry must also have an identifier as well since the daemon uses timestamps to track them. | ||
+ | |||
+ | < | ||
+ | @hourly ID=hourly-backup backups.sh | ||
+ | </ | ||
+ | |||
+ | === root crontab === | ||
+ | |||
+ | ** If using dcron' | ||
+ | |||
+ | While '' | ||
+ | |||
+ | Here's a copy of the contents: | ||
+ | |||
+ | < | ||
+ | # root crontab | ||
+ | # DO NOT EDIT THIS FILE MANUALLY! USE crontab -e INSTEAD | ||
+ | |||
+ | # man 1 crontab for acceptable formats: | ||
+ | # < | ||
+ | # < | ||
+ | |||
+ | # SYSTEM DAILY/ | ||
+ | @hourly | ||
+ | @daily | ||
+ | @weekly | ||
+ | @monthly | ||
+ | </ |