/usr/bin/backup-snaprsync is in chiark-backup 4.4.2build1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 | #!/bin/bash
#
# usage: snaprsync <setting>... <positionals>
#  <setting> is --<name>=<value>
#  <positionals> are assigned to unused mandatory values in order
# mandatory:
#   rhost device mountpoint localarea 
# optional:
	localprevious=
	snapkind=lvm
	rsharedir=/usr/share/chiark-backup 
	retcdir=/etc/chiark-backup
	rvardir=/var/lib/chiark-backup
	bwlimit=
	subdir=.
	rsyncopts=
	rsynccompress=z
	sshopts=
	summer=summer
# snaprsync
#
# This file is part of chiark backup, a system for backing up GNU/Linux and
# other UN*X-compatible machines, as used on chiark.greenend.org.uk.
#
# chiark backup is:
#  Copyright (C) 1997-1998,2000-2001,2007
#                     Ian Jackson <ian@chiark.greenend.org.uk>
#  Copyright (C) 1999 Peter Maydell <pmaydell@chiark.greenend.org.uk>
#
# This 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 3, or (at your option) any later version.
#
# This 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 program; if not, consult the Free Software Foundation's
# website at www.fsf.org, or the GNU Project website at www.gnu.org.
set -e
badusage () { echo >&2 "snaprsync: bad usage: $1"; exit 12; }
nb_echo () { (echo "$@"); } # See Debian #382798
x () { nb_echo "+ $@"; "$@"; }
xspawned () { eval "${1}pid=$!; nb_echo \"+[$!] ($1) &\";"; }
xwait () { eval "nb_echo \"+[\$${1}pid] ($1)...\"; wait \$${1}pid;"; }
while true; do
	case "$1" in
	--?*=*)
		name=${1#--}; name=${name%%=*}
		value=${1#--*=}
		case "$name" in
		rhost|device|mountpoint|localarea);;
		localprevious|snapkind|rsharedir|retcdir|rvardir|bwlimit);;
		subdir|rsyncopts|rsynccompress|sshopts|summer);;
		*) badusage "unknown setting $name";;
		esac
		eval "$name=\$value"
		;;
	--)	shift; break ;;
	-*)	badusage "unknown option $1" ;;
	*)	break ;;
	esac
	shift
done
for name in rhost device mountpoint localarea; do
	eval "value=\$$name"
	if [ "x$value" != x ]; then continue; fi
	if [ $# = 0 ]; then badusage "no value for setting $name"; fi
	eval "$name=$1"
	shift
done
datefmt='%Y-%m-%d %H:%M:%S Z'
rsync="rsync ${bwlimit:+--bwlimit} $bwlimit"
export RSYNC_RSH="ssh -o compression=no $sshopts"
sshpfx='PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin; export PATH; '
ssh $sshopts $rhost "$sshpfx date -u '+$rhost $datefmt start'"
ssh $sshopts $rhost "$sshpfx id"
ssh $sshopts $rhost "$sshpfx ls -d $rsharedir"
ssh $sshopts $rhost "$sshpfx ls -d $rvardir"
test -d $localarea || x mkdir $localarea
ournode=`uname -n`
rsumsfile=for-$ournode.sums
summer="$summer -ACDBtqfx"
td=/dev/enoent
rc=12
trap 'rm -rf $td; exit $rc' 0
td=`mktemp -td`
mkfifo -m 600 $td/sentinel
exec 4<>$td/sentinel
x ssh $sshopts $rhost "$sshpfx $rsharedir/snap-drop $rvardir"
x ssh $sshopts $rhost "
	$sshpfx
	set -e
	cd $rvardir
	echo '$retcdir/snap/$snapkind drop $rvardir' >snap-drop.new
	mv snap-drop.new snap-drop
"
x ssh $sshopts $rhost "$sshpfx $retcdir/snap/$snapkind snap $rvardir $device $mountpoint"
ssh $sshopts $rhost <$td/sentinel 4<&- "
  $sshpfx
  set -e
  date -u '+$rhost $datefmt main'
  exec 3<&0 0</dev/null
  (set +e; read x <&3; kill 0) &
  cd $rvardir
  umask 077
  exec 3>$rsumsfile
  cd snap-mount
  $summer . >&3
  date -u '+$rhost $datefmt sumsdone'
  cd ..
" &
xspawned rsum
x $rsync -aHSx$rsynccompress --numeric-ids --delete $rsyncopts \
	${localprevious:+--link-dest} $localprevious \
	$rhost:$rvardir/snap-mount/$subdir $localarea/.
date -u "+ $datefmt rsyncdone"
exec 3>$localarea,lsums
(cd $localarea && \
 $summer . >&3) &
xspawned lsum
exec 3>&-
xwait rsum
exec 4<&-
date -u "+ $datefmt sumsdone"
x ssh $sshopts $rhost "$sshpfx $rsharedir/snap-drop $rvardir"
if [ "x${localprevious}" != x ] && test -f "$localprevious,rsums"; then
	cp "$localprevious,rsums" "$localarea,rsums"
fi
x $rsync -pI \
	$rhost:$rvardir/$rsumsfile \
	"$localarea,rsums"
xwait $lsum
date -u "+ $datefmt checking"
set +e
diff -u <(sed -e 's/^mountpoint/dir       /' "$localarea,rsums") \
  "$localarea,lsums" >"$localarea,sumsdiff"
diffrc=$?
set -e
test $diffrc = 0 || test $diffrc = 1
date -u "+ $datefmt checked $diffrc"
rc=$diffrc
 |