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GNU GENERAL PUBLIC LICENSE
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How to Apply These Terms to Your New Programs
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Also add information on how to contact you by electronic and paper mail.
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The hypothetical commands `show w' and `show c' should show the appropriate
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The GNU General Public License does not permit incorporating your program
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# btrfs-sync
Smart and easy sync of BTRFS snapshots, locally or through SSH.
![Example](resources/btrfs-sync.gif)
Can be used in conjunction with [btrfs-snp](https://ownyourbits.com/2017/12/27/schedule-btrfs-snapshots-with-btrfs-snp/)
```
# btrfs-sync --verbose --delete /home/user/.snapshots user@server:/media/USBdrive/home-snapshots
* Skip existing '/home/user/.snapshots/monthly_2018-01-09_200102'
* Skip existing '/home/user/.snapshots/monthly_2018-02-08_200102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-09_140102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-16_150102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-23_150102'
* Skip existing '/home/user/.snapshots/weekly_2018-03-02_180102'
* Skip existing '/home/user/.snapshots/daily_2018-03-03_000101'
* Skip existing '/home/user/.snapshots/daily_2018-03-04_080101'
* Skip existing '/home/user/.snapshots/daily_2018-03-05_100102'
* Skip existing '/home/user/.snapshots/daily_2018-03-06_100102'
* Skip existing '/home/user/.snapshots/daily_2018-03-07_110102'
* Synchronizing '/home/user/.snapshots/hourly_2018-03-08_090101' using seed '.snapshots/hourly_2018-03-07_090101'...
time elapsed [0:00:24] | rate [11.1MiB/s] | total size [ 132MiB]
* Synchronizing '/home/user/.snapshots/hourly_2018-03-08_100101' using seed '.snapshots/hourly_2018-03-09_090101'...
time elapsed [0:01:05] | rate [11.1MiB/s] | total size [ 275MiB]
* Deleting non existent snapshots...
Delete subvolume (no-commit): '/media/USBdrive/home-snapshots/hourly_2018-03-08_090101'
Delete subvolume (no-commit): '/media/USBdrive/home-snapshots/hourly_2018-03-08_100101'
```
## Features
- Simple syntax
- Progress indication
- Support for _xz_ or _pbzip2_ compression in order to save bandwidth.
- Retention policy
- Automatic incremental synchronization
- Cron friendly
## Usage
The syntax is similar to that of _scp_
```
Usage:
btrfs-sync [options] <src> [<src>...] [[user@]host:]<dir>
-k|--keep NUM keep only last <NUM> sync'ed snapshots
-d|--delete delete snapshots in <dst> that don't exist in <src>
-z|--xz use xz compression. Saves bandwidth, but uses one CPU
-Z|--pbzip2 use pbzip2 compression. Saves bandwidth, but uses all CPUs
-q|--quiet don't display progress
-v|--verbose display more information
-h|--help show usage
<src> can either be a single snapshot, or a folder containing snapshots
<user> requires privileged permissions at <host> for the 'btrfs' command
```
## Examples
### Manual
Synchronize snapshots of _home_ to a USB drive
```
# btrfs-sync /home/user/.snapshots /media/USBdrive/home-snapshots
```
Synchronize snapshots of _home_ to a USB drive in another machine
```
# btrfs-sync /home/user/.snapshots user@server:/media/USBdrive/home-snapshots
```
Synchronize one snapshot of _home_ to a USB drive in another machine
```
# btrfs-sync /home/user/.snapshots/monthly_2018-02-08_200102 user@server:/media/USBdrive/home-snapshots
```
Synchronize only monthly snapshots of _home_ to a USB drive in another machine
```
# btrfs-sync /home/user/.snapshots/monthly_* user@server:/media/USBdrive/home-snapshots
```
### Cron
Daily synchronization over the internet, keep only last 50
```
cat > /etc/cron.daily/btrfs-sync <<EOF
#!/bin/bash
/usr/local/sbin/btrfs-sync --quiet --keep 50 --xz /home user@host:/path/to/snaps
EOF
chmod +x /etc/cron.daily/btrfs-sync
```
Daily synchronization in LAN, mirror snapshot directory
```
cat > /etc/cron.daily/btrfs-sync <<EOF
#!/bin/bash
/usr/local/sbin/btrfs-sync --quiet --delete /home user@host:/path/to/snaps
EOF
chmod +x /etc/cron.daily/btrfs-sync
```
More at [ownyourbits.com](https://ownyourbits.com)

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#!/bin/bash
#
# Simple script that synchronizes BTRFS snapshots locally or through SSH.
# Features compression, retention policy and automatic incremental sync
#
# Usage:
# btrfs-sync [options] <src> [<src>...] [[user@]host:]<dir>
#
# -k|--keep NUM keep only last <NUM> sync'ed snapshots
# -d|--delete delete snapshots in <dst> that don't exist in <src>
# -z|--xz use xz compression. Saves bandwidth, but uses one CPU
# -Z|--pbzip2 use pbzip2 compression. Saves bandwidth, but uses all CPUs
# -q|--quiet don't display progress
# -v|--verbose display more information
# -h|--help show usage
#
# <src> can either be a single snapshot, or a folder containing snapshots
# <user> requires privileged permissions at <host> for the 'btrfs' command
#
# Cron example: daily synchronization over the internet, keep only last 50
#
# cat > /etc/cron.daily/btrfs-sync <<EOF
# #!/bin/bash
# /usr/local/sbin/btrfs-sync -q -k50 -z /home user@host:/path/to/snaps
# EOF
# chmod +x /etc/cron.daily/btrfs-sync
#
# Copyleft 2018 by Ignacio Nunez Hernanz <nacho _a_t_ ownyourbits _d_o_t_ com>
# GPL licensed (see end of file) * Use at your own risk!
#
# More at https://ownyourbits.com
#
# help
print_usage() {
echo "Usage:
$BIN [options] <src> [<src>...] [[user@]host:]<dir>
-k|--keep NUM keep only last <NUM> sync'ed snapshots
-d|--delete delete snapshots in <dst> that don't exist in <src>
-z|--xz use xz compression. Saves bandwidth, but uses one CPU
-Z|--pbzip2 use pbzip2 compression. Saves bandwidth, but uses all CPUs
-q|--quiet don't display progress
-v|--verbose display more information
-h|--help show usage
<src> can either be a single snapshot, or a folder containing snapshots
<user> requires privileged permissions at <host> for the 'btrfs' command
Cron example: daily synchronization over the internet, keep only last 50
cat > /etc/cron.daily/btrfs-sync <<EOF
#!/bin/bash
/usr/local/sbin/btrfs-sync -q -k50 -z /home user@host:/path/to/snaps
EOF
chmod +x /etc/cron.daily/btrfs-sync
"
}
echov() { [[ "$VERBOSE" == 1 ]] && echo "$@" || true; }
#----------------------------------------------------------------------------------------------------------
# parse arguments
BIN="${0##*/}"
KEEP=0
ZIP=cat PIZ=cat
SILENT=">/dev/null"
OPTS=$( getopt -o hqzZk:dv -l quiet -l help -l xz -l pbzip2 -l keep: -l delete -l verbose -- "$@" 2>/dev/null )
[[ $? -ne 0 ]] && { echo "error parsing arguments"; exit 1; }
eval set -- "$OPTS"
while true; do
case "$1" in
-h|--help ) print_usage; exit 0 ;;
-q|--quiet ) QUIET=1 ; shift 1 ;;
-d|--delete ) DELETE=1 ; shift 1 ;;
-k|--keep ) KEEP=$2 ; shift 2 ;;
-z|--xz ) ZIP=xz PIZ=( xz -d ); shift 1 ;;
-Z|--pbzip2 ) ZIP=pbzip2 PIZ=( pbzip2 -d ); shift 1 ;;
-v|--verbose) SILENT="" VERBOSE=1 ; shift 1 ;;
--) shift; break ;;
esac
done
SRC=( "${@:1:$#-1}" )
DST="${@: -1}"
# detect remote dst argument
[[ "$DST" =~ : ]] && {
NET="$( sed 's|:.*||' <<<"$DST" )"
DST="$( sed 's|.*:||' <<<"$DST" )"
SSH=( ssh -o ServerAliveInterval=5 -o ConnectTimeout=1 "$NET" )
}
[[ "$SSH" != "" ]] && DST_CMD=( ${SSH[@]} ) || DST_CMD=( eval )
#----------------------------------------------------------------------------------------------------------
# checks
## general checks
[[ $# -lt 2 ]] && { print_usage ; exit 1; }
[[ ${EUID} -ne 0 ]] && { echo "Must be run as root. Try 'sudo $BIN'"; exit 1; }
${DST_CMD[@]} true &>/dev/null || { echo "SSH access error to $NET" ; exit 1; }
## src checks
for s in "${SRC[@]}"; do
src="$(cd "$s" &>/dev/null && pwd)" || { echo "$s not found"; exit 1; } #abspath
btrfs subvolume show "$src" &>/dev/null && SRCS+=( "$src" ) || \
for dir in $( ls -drt "$src"/* 2>/dev/null ); do
btrfs subvolume show "$dir" &>/dev/null && SRCS+=( "$dir" )
done
done
[[ ${#SRCS[@]} -eq 0 ]] && { echo "no BTRFS subvolumes found"; exit 1; }
## check pbzip2
[[ "$ZIP" == "pbzip2" ]] && {
type pbzip2 &>/dev/null && \
"${DST_CMD[@]}" type pbzip2 &>/dev/null || {
echo "INFO: 'pbzip2' not installed on both ends, fallback to 'xz'"
ZIP=xz PIZ=unxz
}
}
## use 'pv' command if available
PV=( pv -F"time elapsed [%t] | rate %r | total size [%b]" )
[[ "$QUIET" == "1" ]] && PV=( cat ) || type pv &>/dev/null || {
echo "INFO: install the 'pv' package in order to get a progress indicator"
PV=( cat )
}
#----------------------------------------------------------------------------------------------------------
# sync snapshots
## get dst snapshots ( DSTS, DST_UUIDS )
get_dst_snapshots() {
local DST="$1"
unset DSTS DST_UUIDS
while read entry; do
DST_UUIDS+=( "$( sed 's=|.*==' <<<"$entry" )" )
DSTS+=( "$( sed 's=.*|==' <<<"$entry" )" )
done < <(
"${DST_CMD[@]}" "
DSTS=( \$( ls -d \"$DST\"/* 2>/dev/null ) )
for dst in \${DSTS[@]}; do
UUID=\$( sudo btrfs su sh \"\$dst\" 2>/dev/null | grep 'Received UUID' | awk '{ print \$3 }' )
[[ \"\$UUID\" == \"-\" ]] || [[ \"\$UUID\" == \"\" ]] && continue
echo \"\$UUID|\$dst\"
done"
)
}
## sync incrementally
sync_snapshot() {
local SRC="$1"
local ID LIST PATH_ DATE SECS SEEDS SEED SEED_PATH SEED_ARG
# detect existing
SRC_UUID=$( btrfs su sh "$SRC" | grep "UUID:" | head -1 | awk '{ print $2 }' )
for id in "${DST_UUIDS[@]}"; do
[[ "$SRC_UUID" == "$id" ]] && { echov "* Skip existing '$SRC'"; return 0; }
done
# try to get most recent src snapshot that exists in dst to use as a seed
LIST="$( btrfs subvolume list -su "$SRC" )"
for id in "${DST_UUIDS[@]}"; do
ID=$(btrfs su sh -u "$id" "$SRC" 2>/dev/null|grep "UUID:"|head -1|awk '{print $2}')
PATH_=$( awk "{ if ( \$14 == \"$ID\" ) print \$16 }" <<<"$LIST" )
DATE=$( awk "{ if ( \$14 == \"$ID\" ) print \$11, \$12 }" <<<"$LIST" )
[[ "$ID" == "" ]] || [[ "$PATH_" == "$( basename "$SRC" )" ]] && continue
SECS=$( date -d "$DATE" +"%s" )
SEEDS+=( "$SECS|$PATH_" )
done
SEED="$(for s in "${SEEDS[@]}";do echo "$s";done|sort -V|tail -1|cut -f2 -d'|')"
# incremental sync argument
[[ "$SEED" != "" ]] && {
SEED_PATH="$( dirname "$SRC" )/$( basename $SEED )"
[[ -d "$SEED_PATH" ]] &&
SEED_ARG=( -p "$SEED_PATH" ) || \
echo "INFO: couldn't find $SEED_PATH. Non-incremental mode"
}
# do it
echo -n "* Synchronizing '$src'"
[[ "$SEED_ARG" != "" ]] && echov -n " using seed '$SEED'"
echo "..."
{ btrfs send -q ${SEED_ARG[@]} "$SRC" \
| "$ZIP" \
| "${PV[@]}" \
| "${DST_CMD[@]}" "${PIZ[@]} | sudo btrfs receive \"$DST\" 2>&1 | grep -v '^At subvol '" \
|| exit 1; } | grep -v "^At snapshot "
get_dst_snapshots "$DST" # sets DSTS DST_UUIDS
}
#----------------------------------------------------------------------------------------------------------
# sync all snapshots found in src
get_dst_snapshots "$DST" # sets DSTS DST_UUIDS
for src in "${SRCS[@]}"; do
sync_snapshot "$src"
done
#----------------------------------------------------------------------------------------------------------
# retention policy
[[ "$KEEP" != 0 ]] && \
[[ ${#DSTS[@]} -gt $KEEP ]] && \
echov "* Pruning old snapshots..." && \
for (( i=0; i < $(( ${#DSTS[@]} - KEEP )); i++ )); do
PRUNE_LIST+=( "${DSTS[$i]}" )
done && \
${DST_CMD[@]} sudo btrfs subvolume delete "${PRUNE_LIST[@]}" $SILENT
# delete flag
[[ "$DELETE" == 1 ]] && \
for dst in "${DSTS[@]}"; do
FOUND=0
for src in "${SRCS[@]}"; do
[[ "$( basename $src )" == "$( basename $dst )" ]] && { FOUND=1; break; }
done
[[ "$FOUND" == 0 ]] && DEL_LIST+=( "$dst" )
done
[[ "$DEL_LIST" != "" ]] && \
echov "* Deleting non existent snapshots..." && \
${DST_CMD[@]} sudo btrfs subvolume delete "${DEL_LIST[@]}" $SILENT
# License
#
# This script is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This script is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this script; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place, Suite 330,

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