eolas/Programming_Languages/Shell_Scripting/Cron.md
2022-05-23 19:00:04 +01:00

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---
tags:
- Programming_Languages
- shell
- automation
---
j
In Arch Linux I use `cronie` for cron jobs. (There is no cron service installed by default).
````bash
# View list of cron jobs
crontab -l
# Open cron file
crontab -e
````
\*\*Syntax **
````bash
m h d mon dow command
# minute, hour, day of month, day of week, bash script/args
# 0-59, 0-23, 1-31, 1-12, 0-6
````
**Examples**
Run on the hour every hour
````
0 * * * * mysqlcheck --all-databases --check-only-changed --silent
````
At 01:42 every day:
````
42 1 * * * mysqlcheck --all-databases --check-only-changed --silent
````
**Shorthands**
* `@reboot` Run once, at startup
* `@yearly` Run once a year, “0 0 1 1 \*”.\</>
* `@annually` same as @yearly
* `@monthly` Run once a month, “0 0 1 * \*”
* `@weekly` Run once a week, “0 0 * * 0”
* `@daily` Run once a day, “0 0 * * \*”
* `@midnight` same as @daily
* `@hourly` Run once an hour, “0 * * * \*”
**Examples**
````
@hourly mysqlcheck --all-databases --check-only-changed --silent
````
**View the logs**
````bash
sudo grep crontab syslog
````