tl;dr I used the following code snippets to backup my emacs org files. A quick explanation would be - The cron-job invokes backup_files_to_github.sh, once every 15 minutes, to push modified org files in the ~/org directory to a github repository. You could use this to backup any files.

NOWT=$(date +"%Y-%m-%d %T")
git add .
git commit -m "$NOWT Automated git push"
git push

*/15 * * * * cd ~/org && ./backup_files_to_github.sh >> ~/cron_log.log 2>&1

A better guide for the uninitiated

Backup to git

If you are not familiar with git, please do learn-the-basics-of-git-in-under-10-minutes before you go ahead.

1. Create a github repository (repo) with a readme and clone it to your local machine

2. Copy your files into this folder

3. Copy code snippet 1 to a file named backup_files_to_github.sh and save it in the folder where you have cloned the git repo

4. Make the above file shell script executable

   sudo chmod +x backup_files_to_github.sh
   

   Code Snippet 3: Giving executable permissions to a file

5. Make a few changes in your org files. Invoke the above shell script to see your changes getting uploaded to git

   ./backup_files_to_github.sh
   

   Code Snippet 4: Invoking the shell script

Scheduling backup

We will schedule the shell script invocation using crontab (Quick Read on crontab) and cron.

*/15 * * * * cd ~/org && ./backup_files_to_github.sh >> ~/cron_log.log 2>&1

1. Copy the crontab entry to a file named .crontab in your root directory ~/.crontab. You can choose any directory, I have chosen root here for ease of explanation

2. Run the following commands

   ## List scheduled cronjobs
   crontab -l
   
   ## Invoke crontab to pick the cronjob entries from your file.
   ## This command can be used to refresh the jobs when you modify the .crontab file as well
   crontab ~/.crontab
   
   ## Check if your cronjobs are listed
   crontab -l
   

   Code Snippet 6: crontab commands

3. Once you have run these commands, the files will be backed up every 15^th minute of an hour hh:15, hh:30, hh:45, hh:00

4. If you want to change the frequency of your backup, you can play with cron expressions editor to tweak */15 * * * *

Log rotation

You can avoid log creep, unprecedented growth of log files, in two ways

• Delete this line >> ~/cron_log.log 2>&1 from code-snippet 5 (or)
• Enable log-rotation for the generated logs

I like to have my logs, so I went with log-rotation and achieved it using logrotate. Here is a 10-second guide

1. Install logrotate with homebrew

   brew install logrotate
   
   # This step might fail, we could still try
   brew link logrotate
   

   Code Snippet 7: logrotate installation

2. Create a new file logrotate.conf and save it with the following content

   ~/cron_log.log {
     daily
     rotate 7
     compress
   }
   

   Code Snippet 8: logrotate.conf

3. Force run log rotation to check if it works

   logrotate --force ~/logrotate.conf
   
   ## If brew link failed before, use this command
   ## You might need to replace 3.17.0 with the version that got installed
   /usr/local/Cellar/logrotate/3.17.0/sbin/logrotate --force ~/logrotate.conf
   

   Code Snippet 9: Invoke logrotation

4. Logrotate only works if scheduled, so you would need to update your crontab file (code snippet 2) with another entry for logrotate

   */15 * * * * cd ~/org && ./backup_files_to_github.sh >> ~/cron_log.log 2>&1
   0 11 */1 * * /usr/local/Cellar/logrotate/3.17.0/sbin/logrotate ~/tools/logrotate.conf
   

   Code Snippet 10: cronfile with logrotate updated

5. Invoke crontab ~/.crontab to refresh crontab with the new jobs

That’s a detailed quick guide for backing up files in github.