autosnap-script

A simple shell script for automatically creating and cleaning BTRFS subvolume snapshots. Works on my Arch Linux. Please carefully review the code before using it, as it might corrupt your data!

Required

• BTRFS filesystem + Systemd-boot

Recommended subvolume layout

subvolume	mountpoint
@	/
@home	/home
@log	/var/log
@pkg	/var/cache/pacman/pkg
@.snapshots	/.snapshots
@docker	/var/lib/docker

Features

You can change the following variables at the beginning of the script.

TIMEZONE="Asia/Shanghai"
MOUNT_POINT="/.snapshots/"
SNAPSHOT_DIR="/.snapshots/autosnap"
SUBVOLUME_NAME="@.snapshots"
BOOT_FILE="/boot/loader/entries/arch.conf"

./autosnap.sh

1. Automatically mount @.snapshots subvolume to /.snapshots.
2. Create a directory using today's date (e.g. /.snapshots/autosnap/2023-09-30).
3. If $SNAPSHOT_DIR/$CURRENT_DATE contains a snapshots created within the past hour, it will unmount @.snapshots and exit without any operation.
4. Otherwise, Create a snapshot using btrfs subvolume snapshot / "$SNAPSHOT_DIR/$CURRENT_DATE/@$CURRENT_TIME" (e.g. /.snapshots/autosnap/2023-09-30/@09-00-00).
5. Unmount @.snapshots subvolume and exit.

./autosnap.sh now

Skip step 3 above and create a snapshot now.

./autosnap.sh list

Print all snapshots in /.snapshots/autosnap using tree.

./autosnap.sh list all

Print all snapshots in /.snapshots/autosnap as a list.

./autosnap.sh clean

Delete all snapshots created a week ago.

./autosnap.sh clean all

Delete all snapshots except the one currently mounted at /.

./autosnap.sh clean yesterday

Check the number of snapshots in yesterday's directory, and if it is greater than 1, keep the oldest one and delete all the rest.

./autosnap.sh mount

Mount @.snapshots subvolume to /.snapshots and exit. It will not automatically unmount the snapshots subvolume so that the user can manually inspect it.

./autosnap.sh mount 2023-09-30/@09-00-00

Mount a specified snapshot.

Check if the snapshot specified in the argument exists. If it does, create a Systemd-boot config file backup (e.g. /boot/loader/entries/arch.conf.202309301800.bak) and then modify the mount options in the config file so that the snapshot will be mounted on the next reboot.

./autosnap.sh restore 2023-09-30/@09-00-00

Restore to a specified snapshot.

1. Create a snapshot. (./autosnap.sh now)
2. Backup the snapshot specified in the argument. (e.g. btrfs subvolume snapshot "2023-09-30/@09-00-00" "2023-09-30/@09-00-00.bak")
3. Mount to the specified snapshot. (e.g. ./autosnap.sh mount 2023-09-30/@09-00-00)