iankelling.org Git - distro-setup/blob - btrbk-run

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16
  17 # todo: if we cancel in the middle of a btrfs send, then run again
  18 # immediately, the received subvolume doesn't get a Received UUID:
  19 # field, and we won't mount it. Need to figure out a solution that will
  20 # fix this.
  21
  22
  23 [[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"
  24
  25 source /usr/local/lib/err
  26
  27 usage() {
  28   cat <<'EOF'
  29 btrbk-run [OPTIONS] [run|resume|archive]
  30 usually -t TARGET_HOST or -s SOURCE_HOST
  31
  32 Note, at source location, intentionally not executable, run and read
  33 install-my-scripts.
  34
  35 EOF
  36   echo "top of script file:"
  37   sed -n '1,/^[# ]*end command line/{p;b};q' "$0"
  38   exit $1
  39 }
  40
  41
  42
  43 script_name="${BASH_SOURCE[0]}"
  44 script_name="${script_name##*/}"
  45 pre="${SSH_CLIENT:+$HOSTNAME} $script_name:"
  46 m() { if $verbose; then printf "$pre%s\n"  "$*"; fi;  "$@"; }
  47 e() { printf "$pre%s\n"  "$*"; }
  48 die() { printf "$pre%s\n" "$*" >&2; echo "exiting with status 1" >&2; exit 1; }
  49 mexit() { echo "$pre: exiting with status $1"; exit $1; }
  50
  51 # latest $MAIL_HOST
  52 if [[ -e /b/bash_unpublished/source-state ]]; then
  53   source /b/bash_unpublished/source-state
  54 fi
  55
  56 # note q is owned by root:1000
  57
  58 mountpoints=()
  59
  60 rsync_mountpoint=/q
  61
  62 ret=0
  63 # default options
  64 conf_only=false
  65 dry_run=false # mostly for testing
  66 rate_limit=no
  67 verbose=true; verbose_arg=-v
  68 if [[ $INVOCATION_ID ]]; then
  69   # INVOCATION_ID means running as a systemd service. we cant show progress in this case,
  70   # but if we pass the arg, it will insert mbuffer into the command.
  71   progress_arg=
  72 else
  73   progress_arg="--progress"
  74 fi
  75 incremental_strict=false
  76 pull_reexec=false
  77
  78 default_args_file=/etc/btrbk-run.conf
  79 if [[ -s $default_args_file ]]; then
  80   # shellcheck disable=SC2046 # we want word splitting
  81   set -- $(< $default_args_file) "$@"
  82   # i havent used this feature yet, so warn about it
  83   echo "$0: warning: default btrbk-run options set in $default_args_file (sleeping 5 seconds):"
  84   cat $default_args_file
  85   sleep 5
  86 fi
  87
  88 targets=()
  89 early=false
  90 cron=false
  91 fast=false
  92 kd_spread_maybe=false
  93 orig_args=("$@")
  94 temp=$(getopt -l cron,fast,pull-reexec,help 23ceikl:m:npqrs:t:vh "$@") || usage 1
  95 eval set -- "$temp"
  96 while true; do
  97   case $1 in
  98     # some behaviors specific to running under cron:
  99     # - skip hosts where xprintidle haven't been idle recently
 100     # - if we can't ssh to 1 or more hosts, still do the rest
 101     # - if we aren't MAIL_HOST and no -m or -s, just exit
 102     --cron)
 103       cron=true
 104       pre=
 105       ;;
 106     # for the rare case we want to run multiple instances at the same time
 107     -2) conf_suf=2 ;;
 108     -3) conf_suf=3 ;;
 109     # only creates the config file, does not run btrbk
 110     -c) conf_only=true ;;
 111     # quit early, just btrbk, no extra remounting etc.
 112     -e) early=true ;;
 113     # skip various checks. when we run twice in a row for
 114     # switch mail-host, no need to repeat the same checks again.
 115     --fast) fast=true ;;
 116     -i) incremental_strict=true ;;
 117     # note this implies resume
 118     -k) kd_spread_maybe=true ;;
 119     # bytes per second, suffix k m g
 120     -l) rate_limit=$2; shift ;;
 121     # Comma separated mountpoints to backup. This has defaults set below.
 122     -m) IFS=, mountpoints=($2); unset IFS; shift ;;
 123     -n) dry_run=true ;;
 124     # hide progress
 125     -p) progress_arg= ;;
 126     # internal option for rerunning under newer SOURCE_HOST version.
 127     --pull-reexec) pull_reexec=true;;
 128     # quiet
 129     -q) verbose=false; verbose_arg=; progress_arg= ;;
 130     # source host to receive a backup from
 131     -s)
 132       source=$2
 133       bbksource=$source
 134       if [[ $source == *:* ]]; then
 135         bbksource="[$source]"
 136       fi
 137       shift
 138       ;;
 139     # target hosts to send to. empty is valid for just doing local
 140     # snapshot. we have default hosts we will populate.
 141     -t) IFS=, targets=($2); unset IFS; shift ;;
 142     # verbose.
 143     -v) verbose=true; verbose_arg=-v ;;
 144     -h|--help) usage ;;
 145     --) shift; break ;;
 146     *) die "Internal error!" ;;
 147   esac
 148   shift
 149 done
 150
 151 if $kd_spread_maybe; then
 152   if [[ $1 && $1 != resume ]]; then
 153     die "dont pass -k without resume or empty run arg"
 154   fi
 155   cmd_arg=resume
 156 fi
 157
 158
 159 cmd_arg=${1:-run}
 160
 161
 162 std_preserve="36h 14d 8w 24m"
 163 q_preserve="18h 14d 8w"
 164
 165 case $cmd_arg in
 166   run|resume) : ;;
 167
 168   # This works better than the normal archive command. We have to
 169   # specify the mount points, but that is what we are used to doing and
 170   # we prefer it. Another difference is that archive works recursively
 171   # and we don't care about that. Sometimes we may still want to run
 172   # btrbk archive, but it doesn't even use the config file, so just
 173   # run it directly, eg:
 174   # time s btrbk -v archive /mnt/r7/amy/boot/btrbk ssh://bo/mnt/boot2/btrbk
 175   archive)
 176     cmd_arg=resume
 177     std_preserve="999h 999d 999w 999m"
 178     q_preserve="$std_preserve"
 179     preserve_arg=-p
 180     ;;
 181   *) die "untested command arg" ;;
 182 esac
 183
 184 if (( $# > 1 )); then
 185   die: "only 1 nonoption arg is supported"
 186 fi
 187
 188 if [[ -v targets && $source ]]; then
 189   # note, this doesnt need to be the case, but
 190   # we would need to think about it.
 191   die "error: -t and -s are mutually exclusive"
 192 fi
 193
 194 ### end options parsing
 195
 196 # remove path from earlier version of btrbk
 197 rm -f /usr/sbin/btrbk
 198 # note, this still works as intended if there is no /usr/bin/btrbk
 199 if [[ /a/opt/btrbk/btrbk -nt /usr/bin/btrbk ]]; then
 200   if [[ -e /b/distro-functions/src/package-manager-abstractions ]]; then
 201     . /b/distro-functions/src/package-manager-abstractions
 202     pi asciidoctor
 203   fi
 204   cd /a/opt/btrbk
 205   m make install
 206 fi
 207
 208 # TODO: i wonder if there should be an option to send to the default
 209 # targets, plus any given on the command line.
 210
 211
 212
 213 kd_spread=false
 214 # set default targets
 215 if [[ ! -v targets && ! $source ]]; then
 216   if $cron; then
 217     if [[ $HOSTNAME != "$MAIL_HOST" ]]; then
 218       if $kd_spread_maybe && [[ $HOSTNAME == kd && $MAIL_HOST == x3 ]]; then
 219         if ping -q -c1 -w1 x3.office.fsf.org &>/dev/null; then
 220           work_host=x3.office.fsf.org
 221         elif ping -q -c1 -w1 x3wg.b8.nz &>/dev/null; then
 222           work_host=x3wg.b8.nz
 223         fi
 224         if [[ $work_host ]]; then
 225           source_state="$(ssh $work_host cat /a/bin/bash_unpublished/source-state)"
 226           eval "$source_state"
 227           if [[ $MAIL_HOST == x3 ]]; then
 228             kd_spread=true
 229           else
 230             echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 231             mexit 0
 232           fi
 233         else
 234           echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 235           mexit 0
 236         fi
 237       else
 238         echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 239         mexit 0
 240       fi
 241     fi
 242   fi
 243
 244   at_work=false
 245   at_home=false
 246
 247   case $HOSTNAME in
 248     kw|kd|frodo|x2|x3|sy) : ;;
 249     *)
 250       die "error: no default targets for this host, use -t"
 251       ;;
 252   esac
 253
 254   case $HOSTNAME in
 255     kw)
 256       at_work=true
 257       ;;&
 258     kd|frodo)
 259       at_home=true
 260       ;;&
 261     x2|x3|sy)
 262       if [[ $(dig +short @10.2.0.1 -x 10.2.0.2 2>&1 ||:) == kd.b8.nz. ]] \
 263            && ip n show 10.2.0.1 | grep . &>/dev/null; then
 264         at_home=true
 265       elif ping -q -c1 -w1 hal.office.fsf.org &>/dev/null \
 266           && ip n show 192.168.0.26 | grep . &>/dev/null; then
 267         at_work=true
 268       fi
 269       ;;&
 270     *)
 271       if $at_home; then
 272         if ! $kd_spread && [[ $HOSTNAME != x3 ]]; then
 273           # main work machine
 274           if ping -q -c1 -w1 x3.office.fsf.org &>/dev/null; then
 275             targets+=(x3.office.fsf.org)
 276           elif ping -q -c1 -w1 $h.b8.nz &>/dev/null; then
 277             # in case we took it home
 278             targets+=(x3.b8.nz)
 279           else
 280             targets+=(x3wg.b8.nz)
 281           fi
 282         fi
 283         # temporarily disabled while doing recovery
 284         #        for h in frodo kd; do
 285         for h in kd; do
 286           if [[ $HOSTNAME == "$h" ]]; then
 287             continue
 288           fi
 289           targets+=($h.b8.nz)
 290         done
 291         for h in x2 sy; do
 292           if [[ $HOSTNAME == "$h" ]]; then
 293             continue
 294           fi
 295           if ping -q -c1 -w1 $h.b8.nz &>/dev/null; then
 296             targets+=($h.b8.nz)
 297           elif ping -q -c1 -w1 ${h}w.b8.nz &>/dev/null; then
 298             targets+=(${h}w.b8.nz)
 299           fi
 300         done
 301       elif $at_work; then
 302         if ping -q -c1 -w1 iank.vpn.office.fsf.org &>/dev/null; then
 303           targets+=(iank.vpn.office.fsf.org)
 304         else
 305           targets+=(i.b8.nz)
 306         fi
 307         for h in x2 x3 kw; do
 308           if [[ $HOSTNAME == "$h" ]]; then
 309             continue
 310           fi
 311           if ping -q -c1 -w1 $h.office.fsf.org &>/dev/null; then
 312             targets+=($h.office.fsf.org)
 313           fi
 314         done
 315       else
 316         targets+=(i.b8.nz)
 317       fi
 318       ;;
 319   esac
 320 fi
 321
 322 if $verbose; then
 323   printf "$pre options: conf_only=%s\ndry_run=%s\nrate_limit=%s\nverbose=%s\ncmd_arg=%s" "$conf_only" "$dry_run" "$rate_limit" "$verbose" "$cmd_arg"
 324 fi
 325
 326
 327 if [[ -v targets ]]; then
 328   echo "targets: ${targets[*]}"
 329 fi
 330
 331 if [[ $source ]]; then
 332   echo "source: $source"
 333 fi
 334
 335 if [[ ${mountpoints[0]} ]]; then
 336   for mp in ${mountpoints[@]}; do
 337     if [[ -e /nocow/btrfs-stale/$mp ]]; then
 338       die "error: $mp is stale, mount-latest-subvol first"
 339     fi
 340   done
 341 else
 342   # set default mountpoints
 343   if [[ ${targets[0]} == tp ]]; then
 344     prospective_mps=(/a)
 345   else
 346     case $HOSTNAME in
 347       *)
 348         prospective_mps=()
 349         if [[ $source ]]; then
 350           source_state="$(ssh $source cat /a/bin/bash_unpublished/source-state)"
 351           eval "$source_state"
 352           source_host="$(ssh $source cat /etc/hostname)"
 353           if [[ $source_host == "$MAIL_HOST" ]]; then
 354             prospective_mps+=(/o)
 355           fi
 356           if [[ $source_host == "$HOST2" ]]; then
 357             prospective_mps+=(/a /ar /qr /q)
 358           fi
 359         else
 360           if [[ $HOSTNAME == "$MAIL_HOST" ]]; then
 361             prospective_mps+=(/o)
 362           fi
 363           if [[ $HOSTNAME == "$HOST2" ]]; then
 364             prospective_mps+=(/a /ar /qr /q)
 365           fi
 366           if $kd_spread; then
 367             prospective_mps=(/a /ar /o /qr /q)
 368           fi
 369         fi
 370         # note: put q last just in case its specific retention options were to
 371         # affect other config sections. I havent tested if that is the case.
 372         ;;
 373     esac
 374   fi
 375   for mp in ${prospective_mps[@]}; do # default mountpoints to sync
 376     if [[ -e /nocow/btrfs-stale/$mp ]]; then
 377       e "warning: $mp stale, not adding to default mountpoints"
 378       continue
 379     fi
 380     if awk '{print $2}' /etc/fstab | grep -xF $mp &>/dev/null; then
 381       mountpoints+=($mp)
 382     fi
 383   done
 384 fi
 385
 386 if (( ! ${#mountpoints[@]} )); then
 387   die didnt get mountpoint arg and had no defaults
 388 fi
 389
 390 echo "mountpoints: ${mountpoints[*]}"
 391
 392 ##### end command line parsing ########
 393
 394 # todo: this has a timing problem, since btrbk.timer could activate the service after this check.
 395 if ! $fast && [[ $source ]]; then
 396   if [[ $(ssh $source ps --no-headers -o comm 1) == systemd ]]; then
 397     status=$(ssh $source systemctl is-active btrbk.service) || : # normally returns 3
 398     case $status in
 399       inactive|failed) : ;;
 400       *)
 401         echo "$0: error: cron btrbk is running on source. exiting out of caution"
 402         mexit 1
 403     esac
 404   fi
 405 fi
 406
 407 # pull_reexec stops us from getting into an infinite loop if there is some
 408 # kind of weird problem
 409 pulla=false
 410 for m in "${mountpoints[@]}"; do
 411   if [[ $m == /a ]]; then
 412     pulla=true
 413     break
 414   fi
 415 done
 416 if ! $pull_reexec && [[ $source ]] && $pulla ; then
 417   tmpf=$(mktemp)
 418   m rsync -ra $source:/usr/local/bin/{mount-latest-subvol,check-subvol-stale} /usr/local/bin
 419   m rsync -ra $source:/usr/local/lib/err /usr/local/lib
 420   m scp $source:/a/bin/distro-setup/btrbk-run $tmpf
 421   if ! diff -q $tmpf ${BASH_SOURCE[0]}; then
 422     e "found different version on host $source. reexecing"
 423     install -T $tmpf /usr/local/bin/btrbk-run
 424     m /usr/local/bin/btrbk-run --pull-reexec "${orig_args[@]}"
 425     mexit 0
 426   fi
 427 fi
 428
 429
 430 if ! command -v btrbk &>/dev/null; then
 431   die "error: no btrbk binary found"
 432 fi
 433
 434 if ! $fast; then
 435   # if our mountpoints are from stale snapshots,
 436   # it doesn't make sense to do a backup.
 437   m check-subvol-stale ${mountpoints[@]} || die "found stale mountpoints in ${mountpoints[*]}"
 438
 439   # for an initial run, btrbk requires the dir to exist.
 440   mkdir -p /mnt/{root,o}/btrbk
 441 fi
 442 local_zone=$(date +%z)
 443
 444 if [[ $source ]]; then
 445   if $fast; then
 446     zone=$local_zone
 447   else
 448     if ! zone=$(ssh root@$source date +%z); then
 449       if $conf_only; then
 450         echo "$0: warning: failed to ssh to root@$source"
 451       else
 452         die failed to ssh to root@$source
 453       fi
 454     fi
 455     if [[ $zone != "$local_zone" ]]; then
 456       die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
 457     fi
 458   fi
 459 else
 460
 461   sshable=()
 462   sshfail=()
 463   for h in ${targets[@]}; do
 464     if $fast || $conf_only; then
 465       # Use some typical values in this case
 466       root_size=$(( 1024 * 1024 * 2000 )) #2tb
 467       percent_used=10
 468       zone=$(date +%z)
 469     elif remote_str=$(timeout -s 9 6 ssh root@$h "mkdir -p /mnt/root/btrbk /mnt/o/btrbk && date +%z && df --output=size,pcent / | tail -n1"); then
 470       mapfile -t tmp_array <<<"$remote_str"
 471       zone="${tmp_array[0]}"
 472       IFS=" " read -r root_size percent_used <<<"${tmp_array[1]}"
 473       percent_used=${percent_used%%%}
 474
 475       if (( ${#tmp_array[@]} != 2 )); then
 476         die "error: didnt get 2 lines in test ssh to target $h. investigate"
 477       fi
 478       case $percent_used in
 479         [0-9]|[1-9][0-9]) : ;;
 480         *)
 481           die "error: didnt get percent disk use in test ssh to target $h. investigate"
 482           ;;
 483       esac
 484     else
 485       sshfail+=($h)
 486       continue
 487     fi
 488
 489     # we may be booted into a bootstrap fs or something
 490     min_root_kb=$(( 1024 * 1024 * 200 )) # 200 gb
 491     if (( root_size < min_root_kb )); then
 492       continue
 493     fi
 494
 495     if (( percent_used >= 98 )); then
 496       die "error: filesystem on target $h is $percent_used % full"
 497     fi
 498
 499     # on sy, xprintidle is resetting every 12 seconds even when not
 500     # idle, i dunno why, instead we are checking if the screen is locked,
 501     # which is good enough.
 502     #
 503     # This is a separate ssh because the command can fail and thatis ok.
 504     if $cron; then
 505       locked=false
 506       if lock_info=$(timeout -s 9 6 ssh $h DISPLAY=:0 xscreensaver-command -time); then
 507         if [[ $lock_info != *non-blanked* ]]; then
 508           locked=true
 509         fi
 510       else
 511         locked=true
 512       fi
 513       if ! $locked; then
 514         # Ignore this host. i sometimes use a non-main machine for
 515         # testing or web browsing, knowing that everything will be wiped
 516         # by the next backup, but I dont want it to happen as Im using
 517         # it from cronjob.
 518         e "warning: $h: seems to be actively in use, skipping for now"
 519         continue
 520       fi
 521     fi
 522     sshable+=($h)
 523     if [[ $zone != "$local_zone" ]]; then
 524       die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
 525     fi
 526   done
 527   if [[ ! ${sshable[*]} ]] || { ! $cron && [[ ${sshfail[*]} ]]; }; then
 528     die "failed to ssh to hosts: ${sshfail[*]}"
 529   else
 530     if [[ ${sshfail[*]} ]]; then
 531       ret=1
 532       e "error: failed to ssh to ${sshfail[*]} but continuing with other hosts"
 533     fi
 534     targets=(${sshable[@]})
 535   fi
 536 fi
 537
 538
 539 cat >/etc/btrbk$conf_suf.conf <<EOF
 540 ssh_identity /q/root/h
 541 #ssh_identity /root/.ssh/home
 542
 543 # Just a guess that local7 is a good facility to pick.
 544 # It's a bit odd that the transaction log has to be logged to
 545 # a file or syslog, while other output is sent to std out.
 546 # The man does not mention a way for them to be together, but
 547 # I dunno if setting a log level like warn might also output
 548 # transaction info.
 549 transaction_syslog local7
 550
 551 # trying this out
 552 #stream_compress zstd
 553
 554 # so we only run one at a time
 555 lockfile                   /var/lock/btrbk$conf_suf.lock
 556
 557 # default format of short does not accomidate hourly preservation setting
 558 timestamp_format long-iso
 559
 560 # only make a snapshot if things have changed
 561 snapshot_create onchange
 562 # I could make this different from target_preserve,
 563 # if one disk had less space.
 564 # for now, keeping them equal.
 565 snapshot_preserve $std_preserve
 566 snapshot_preserve_min 2h
 567 snapshot_dir btrbk
 568 # so, total backups = ~58
 569 target_preserve $std_preserve
 570 target_preserve_min 2h
 571
 572 # i tried this when investigating: clone no source subvolume found error
 573 #incremental_prefs sro:1 srn:1 sao san:1 aro:1 arn:1
 574
 575 # if something fails and it's not obvious, try doing
 576 # btrbk -l debug -v dryrun
 577
 578 rate_limit $rate_limit
 579 EOF
 580
 581 if $incremental_strict; then
 582   cat >>/etc/btrbk$conf_suf.conf <<EOF
 583 incremental strict
 584 EOF
 585 fi
 586
 587 qconf() {
 588   case $sub in
 589     q)
 590       # q has sensitive data i dont want to backup for so long
 591       cat >>/etc/btrbk$conf_suf.conf <<EOF
 592 snapshot_preserve $q_preserve
 593 snapshot_preserve_min 2h
 594 snapshot_dir btrbk
 595 target_preserve $q_preserve
 596 target_preserve_min 2h
 597 EOF
 598       ;;
 599   esac
 600
 601 }
 602
 603 # make /q be last
 604 mp_count=${#mountpoints[@]}
 605 for (( i=0; i < mp_count - 1 ; i++ )); do
 606   if [[ ${mountpoints[i]} == /q ]]; then
 607     unset "mountpoints[i]"
 608     mountpoints+=(/q)
 609   fi
 610 done
 611
 612 for m in ${mountpoints[@]}; do
 613   case $m in
 614     /o)
 615       vol=/mnt/o
 616       ;;
 617     *)
 618       vol=/mnt/root
 619       ;;
 620   esac
 621
 622   sub=${m#/}
 623   if [[ $source ]]; then
 624     cat >>/etc/btrbk$conf_suf.conf <<EOF
 625 volume ssh://$bbksource$vol
 626 subvolume $sub
 627 EOF
 628     qconf
 629     cat >>/etc/btrbk$conf_suf.conf <<EOF
 630 target send-receive $vol/btrbk
 631 EOF
 632   fi
 633   if (( ${#targets[@]} )); then
 634     cat >>/etc/btrbk$conf_suf.conf <<EOF
 635 volume $vol
 636 subvolume $sub
 637 EOF
 638     qconf
 639     for tg in ${targets[@]}; do
 640       # handle ipv6
 641       if [[ $tg == *:* ]]; then
 642         tg="[$tg]"
 643       fi
 644       cat >>/etc/btrbk$conf_suf.conf <<EOF
 645 target send-receive ssh://$tg$vol/btrbk
 646 EOF
 647     done
 648   fi
 649 done
 650
 651 # todo: umount first to ensure we don't have any errors
 652 # todo: do some kill fuser stuff to make umount more reliable
 653
 654
 655 if $conf_only; then
 656   mexit 0
 657 fi
 658
 659
 660
 661 if $dry_run; then
 662   m btrbk -c /etc/btrbk$conf_suf.conf -v -n $cmd_arg
 663   mexit 0
 664 fi
 665 # -q and just using the syslog option seemed nice,
 666 # but it doesn't show when a send has a parent and when it doesn't.
 667 m btrbk -c /etc/btrbk$conf_suf.conf $preserve_arg $verbose_arg $progress_arg $cmd_arg
 668
 669 if $early; then
 670   exit 0
 671 fi
 672
 673 # todo: tp not valid anymore.
 674 # if we have it, sync to systems which don't
 675 if mountpoint $rsync_mountpoint >/dev/null; then
 676   for tg in ${targets[@]}; do
 677     case $tg in
 678       tp)
 679         dirs=(/p/c/machine_specific/tp)
 680         for x in /p/c/machine_specific/*.hosts; do
 681           if grep -qxF $tg $x; then
 682             dirs+=(${x%.hosts})
 683           fi
 684         done
 685         m rsync -aSAXPH --specials --devices --delete --relative ${dirs[@]} root@$tg:/
 686         ;;
 687     esac
 688   done
 689 fi
 690
 691 subvols=()
 692 for mp in "${mountpoints[@]}"; do
 693   subvols+=("${mp##*/}")
 694 done
 695 if [[ $source ]]; then
 696   m mount-latest-subvol "${subvols[@]}"
 697 else
 698   for tg in ${targets[@]}; do
 699     m /a/exe/mount-latest-remote "$tg" "${subvols[@]}" || ret=$?
 700   done
 701 fi
 702
 703 if [[ $ret == 0 ]]; then
 704   for tg in ${targets[@]}; do
 705     :
 706     #ssh root@$tg /a/exe/mail-backup-clean
 707   done
 708 fi
 709
 710 mexit $ret
 711
 712 # todo: move variable data we don't care about backing up
 713 # to /nocow and symlink it.
 714
 715
 716 # background on btrbk timezones. with short/long, timestamps use local time.
 717 # for long, if your local time moves backwards, by moving timezones or
 718 # for an hour when daylight savings changes it, you will temporarily get
 719 # a more aggressive retention policy for the overlapping period, and
 720 # vice versa for the opposite timezone move. The alternative is using
 721 # long-iso, which puts timezone info into the timestamp, which means
 722 # that instead of shifting time, you shift the start of day/week/month
 723 # which is used for retention to your new local time, which means for
 724 # example, if you moved forward by 8 hours, the daily/weekly/monthly
 725 # retention will be 8 hours more aggressive since midnight is at a new
 726 # time, unless you fake the timzeone using the TZ env variable.
 727 # However, in the short term, there will be no inconsistencies.
 728 # I don't see any problem with shifting when the day starts for
 729 # retention, so I'm using long-iso.
 730
 731 # note to create a long-iso timestamp: date +%Y%m%dT%H%M%S%z