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btrfs_snapshot.sh - create snapshot for btrfs mountpoints/volumes (and send to another btrfs backup directory)
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#!/bin/bash | |
# v. 2023.05.20 | |
MOUNTPOINTS=('/' '/home') | |
RETAINSNAPS=2 # snapshots in SNAPSHOTDIRNAME | |
BACKUPDIR='/mnt/backup' # optional, set SENDTOBACKUP=yes | |
SENDTOBACKUP=no # send to BACKUPDIR: yes or no | |
SNAPSHOTDIRNAME='.snapshots' | |
function is_btrfs { | |
local FS=$(stat -f --format=%T "$1") | |
[ "$FS" = "btrfs" ] && return 0 | |
return 1 | |
} | |
function is_btrfs_volume { | |
findmnt -rn "$1" | grep "subvol=" > /dev/null 2>&1 && return 1 # return false if path is a mountpoint | |
btrfs subvolume show "$1" > /dev/null 2>&1 && return 0 | |
return 1 | |
} | |
function is_btrfs_mountpoint { | |
findmnt -rn "$1" | grep "subvol=" > /dev/null 2>&1 && return 0 | |
return 1 | |
} | |
function create_snapshot { | |
local mountpoint=$1 | |
local snapdir="$SNAPSHOTDIRNAME" | |
local date=$(date +%Y%m%d-%H%M%S) | |
local snaproot | |
local vol | |
local isbtrfsvolume | |
local snapcount | |
local lastvol | |
local allsnapsarray | |
local snapstoremovecount | |
if [[ "$SENDTOBACKUP" == "yes" ]]; then | |
if ! is_btrfs "$BACKUPDIR" ; then | |
echo \"$BACKUPDIR\" is not a btrfs!! Exit. | |
exit 1 | |
fi | |
fi | |
if [[ "$mountpoint" != "/" ]]; then mountpoint=${mountpoint%/}; fi; # remove trainling slash for any dir except root (/) | |
# find btrfs volume name for path | |
if is_btrfs_volume "$mountpoint"; then | |
vol=$mountpoint | |
echo \"$mountpoint\" is volume | |
elif is_btrfs_mountpoint "$mountpoint"; then | |
vol=$(findmnt -rn "$mountpoint" | awk -F "subvol=" 'NR==1 {print $2}') | |
echo \"$mountpoint\" is mountpoint | |
else | |
echo \"$mountpoint\" is not a btrfs mountpoint or volume!! Exit. | |
exit 1 | |
fi | |
if [[ "$vol" == "/" ]]; then | |
vol='@btrfsroot' | |
else | |
vol="${vol:1}" # remove lead slash | |
vol="${vol//'/'/__}" # replace slashes by __ | |
fi | |
echo "mp: $mountpoint" | |
echo "vol: $vol" | |
snaproot="${mountpoint}/${snapdir}" | |
mkdir -p "$snaproot" > /dev/null 2>&1 | |
btrfs sub snap -r "${mountpoint}" "${snaproot}/@snp_${vol}_ro_${date}" || exit 1 | |
if [[ "$SENDTOBACKUP" == "yes" ]]; then | |
snapcount=$(ls "$snaproot" | grep "@snp_${vol}_ro" | wc -l) | |
if [[ "$snapcount" == "1" ]]; then | |
btrfs send "${snaproot}/@snp_${vol}_ro_${date}" | btrfs receive "$BACKUPDIR" | |
else | |
lastvol=$(ls "$snaproot" | grep "@snp_${vol}_ro" | tail -2 | head -n -1) | |
btrfs send -p "${snaproot}/${lastvol}" "${snaproot}/@snp_${vol}_ro_${date}" | btrfs receive "$BACKUPDIR" | |
fi | |
fi | |
if [ "$RETAINSNAPS" -gt "0" ]; then | |
allsnapsarray=($(ls "$snaproot" | grep "@snp_${vol}_ro")) | |
if [ "$RETAINSNAPS" -lt "${#allsnapsarray[@]}" ]; then | |
snapstoremovecount=$(( ${#allsnapsarray[@]} - $RETAINSNAPS )) | |
for ((i=0;i<$snapstoremovecount;i++)); do | |
btrfs subvolume delete "${snaproot}/${allsnapsarray[$i]}" | |
done | |
fi | |
fi | |
echo "" | |
} | |
for mp in ${MOUNTPOINTS[*]}; do | |
create_snapshot "$mp" | |
done |
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