Rsync (Remote Sync) is a very reliable and popular tool used for mirroring and syncing files across computer systems, particularly in Unix/Linux. To use rsync to sync files at specific times, you will need to integrate it with a scheduling utility in Unix/Linux like Cron.
Cron is a Linux feature that allows you to schedule tasks. You can use it to automate rsync commands at specific times, for an example, you can schedule a daily data backup at midnight.
Below is a simple five-step guide on how you can sync files at specific times by using both rsync and Cron:
1. Launch a cron editor: This is done by using the crontab command. In your terminal, type `crontab -e`. This will open the cron configuration file in your default text editor.
1. Write a cron job: Specify the time you prefer the task to be initialized in this job. The general format is Minute (0 – 59) , Hour (0 – 23), Day of month (1-31), Month (1 – 12), Day of week (0 – 7 where 0 and 7 are Sunday) followed by the command to run.
For an instance, if you want to sync your files every day at 3 am, your cron job should resemble `0 3 * * * /usr/bin/rsync -av /source_dir/ /destination_dir/`
1. Save the file: Exit the editor by saving the changes. This will automatically install your new cron job.
1. Check your cron job: You can check the cron job list by using the command `crontab -l`. This will list all the cron jobs configured in your system.
1. Monitor your tasks: You can monitor your tasks by checking the system logs.
It’s critical to note that both the source and destination directories in the rsync command above should be replaced with the directories you wish to sync from and to respectively.
Keep in mind that the above cron job entry won’t create logs. If need to create a log file to check if everything is working smoothly or done correctly, you can modify your cron job to `0 3 * * * /usr/bin/rsync -av /source_dir/ /destination_dir/ > /home/user/rsync.log`.
The examples in this response were primarily obtained from guides and tutorials on rsync and Cron found at Linux Handbook (https://linuxhandbook.com/rsync-command-examples/) and nixCraft (https://www.cyberciti.biz/faq/how-do-i-add-jobs-to-cron-under-linux-or-unix-oses/), and these sites can be visited for more exhaustive guidance on rsync and Cron usage.Overall, understanding rsync and Cron commands is essential, but also make sure the user under which cron job is running has enough permissions to access and execute source and destination directories. If not, you may run into permission errors.
