Backup Android folders using rsync

Installation

• Install Termux and Termux:API (e.g. from F-Droid).
• Activate the storage in
  Termux.
• Install the dependencies apt install rsync openssh jq.
• Generate ssh key ssh-keygen.
• Copy ssh key to destination ssh-copy-id user@host.
• Copy android-rsync-backup (e.g in your home folder).
• Edit variables src, dest and ssid in android-rsync-backup script.

Manual backup

Run the script from Termux: ~/android-rsync-backup or add the script to homescreen with Termux:Widget.

Periodic backup with cron

• Activate cron crond
• Add android-rsync-backup to crontab
• Set ACQUIRE WAKELOCK for Termux

Activate the backup using Tasker

See Termux:Task.