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**oshunluvr** · Dec 31, 2018, 09:28 AM

The daily snapshot script:

Code:

#!/bin/bash#
# IMPORTANT:
# This script requires the root btrfs file system be mounted somewhere before running.
# Alternately, have the mount declared in fstab and the script will mount it.
#
exec 1> >(logger -s -t $(basename $0)) 2>&1 # Log the script activity


## Set the variables. Edit this section as needed
# declare an array variable of all target subvolumes
declare -a SUBVLIST=("@grub" "@KDEneon1804" "@KDEneon1804_home" "@KDEneon" "@KDEneon_home" "@Kubuntu_1804")


# other variables
NOTIFYUSER="stuart"                     # the username to get error messages
NOTIFYDISPLAY=":0.0"                    # the above user's X session
source_folder="/subvol/"                # Root file system mount location
snapshot_folder="/subvol/snapshots/"    # Snapshots folder
addname="_daily_"                       # This is added to the subvolume name of the daily snapshots
lastsnapnum=6                           # Last snapshot number to be saved before moving to backup status


# Verify the root BTRFS file system is mounted and mount it if not, or fail;
if [ -d "$source_folder" ]; then
    if ! mountpoint -q "$source_folder"; then
        mount "$source_folder"
        if ! mountpoint -q "$source_folder"; then 
            su $NOTIFYUSER -c "export DISPLAY=${NOTIFYDISPLAY}; /usr/bin/notify-send -i ksnapshot -t 0 'Daily snapshots:' 'Daily snapshot operation failed - no mountable subvolume folder.'"
            exit 1
        fi
    fi
    else 
        su $NOTIFYUSER -c "export DISPLAY=${NOTIFYDISPLAY}; /usr/bin/notify-send -i ksnapshot -t 0 'Daily snapshots:' 'Daily snapshot operation failed - subvolume folder incorrect.'"
        exit 1
fi


## Begin process
# loop through the list of subvolumes
for SUBV in "${SUBVLIST[@]}"; do
    SUBVPATH="$source_folder""$SUBV"
    SUBVSNAP="$snapshot_folder""$SUBV"


# Move last daily snapshot to backup status
    if [[ -d "$SUBVSNAP""$addname""$lastsnapnum" ]]; then
        btrfs su de -c "$SUBVSNAP""_backup"
        mv "$SUBVSNAP""$addname""$lastsnapnum" "$SUBVSNAP""_backup"
        btrfs pr set -ts "$SUBVSNAP""_backup" ro true
    fi


# Roll the current snapshot names by adding 1 to each trailing number
    for ((i="$lastsnapnum-1";i>=0;i--)); do
        if [[ -d "$SUBVSNAP""$addname"$i ]]; then
        mv "$SUBVSNAP""$addname"$i "$SUBVSNAP""$addname"$(($i+1)); fi
    done


# Take new read-only snapshot
    btrfs su sn "$SUBVPATH" "$SUBVSNAP""$addname""0"
    touch "$SUBVSNAP""$addname""0"
done


# Notify the user that the job is done
su $NOTIFYUSER -c "export DISPLAY=${NOTIFYDISPLAY}; /usr/bin/notify-send -i ksnapshot -t 0 'Daily snapshots:' 'Daily snapshot operation complete.'"


# Script complete
exit 0

Takes a snapshot every morning of all the subvolumes listed in the array variable defined in this way:

Code:

# declare an array variable of all target subvolumes
declare -a SUBVLIST=("@grub" "@KDEneon1804" "@KDEneon1804_home" "@KDEneon" "@KDEneon_home" "@Kubuntu_1804")

and then used this way:

Code:

for SUBV in "${SUBVLIST[@]}"; do

To my eye, it's cleaner to have the list at the top of the script rather than buried further down.

Notes and the sequence of events for this script. For each subvolume in the array list;
1) Prepare a snapshot for use as a backup.

I wanted a single week of snapshots, then a backup so the script creates snapshots 0 to 5 (that's six snapshots) then names the 7th as "backup" and sets it as read-only to prepare it for the send|receive operation. The backup snapshot will be created daily but may not be used every day so it deletes the existing backup snapshot and replaces it with snapshot "6". You could lengthen or shorten the cycle by changing the "lastnumsnap" to a different number.

2) Rename all existing snapshots (eventually 6 plus the backup snapshot) by increasing the trailing digit in the snapshot name by one.

Today's snapshot ends in "0". yesterday's in "1", the day before in "2", and so on. Again, the length of this cycle is set by "lastnumsnap". "6" in this variable is 7 snapshots because I start with 0.

3) Take a new "0" snapshot for today.

Note that there a three locations where I have it notify the user set in the variables (thanks again kubicle) to let you know if the thing worked or failed. I should probably increase the amount of error checking and notifications, but this seemed like enough at this point.

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Automating snapshots and backups

Automating snapshots and backups

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