28 lines
823 B
Markdown
28 lines
823 B
Markdown
# Crontab
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Run programs at a given time. Useful for system cleanups and updates
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```bash
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crontab -e
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```
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Edit your crontab file
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Syntax looks like (min, hour, day, month, year). Note these are absolute values,
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so putting something like `* 1 * * *` will run the program at `1:00am` every
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day. To understand these times use [this](https://crontab.guru/) Example crontab
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file:
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```bash
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PATH=/usr/local/bin:/bin:/usr/bin
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HOME=/home/emiliko
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* * * * * ~/program_1.sh # Every minute, on the minute
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* * * * * (sleep 30; ~/program_1.sh) # Every minute at 30s in
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1 * * * * ~/program_2.sh # Every hour at :01 minute
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1 * 3 * * ~/program_3.sh # Every day at 3:01am
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```
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Since crontab doesn't support resolutions greater than 1 minute, a workaround
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with `sleep` can be used instead. `program_1.sh` above effectively runs every
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30s
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