backup/remount

   1 #!/bin/sh
   2
   3 set -e
   4
   5 removes () {
   6         rm -f -- "$vardir/snap-mount" "$vardir/snap-device"
   7 }
   8
   9 vardir="$2"
  10
  11 case "$#.$1" in
  12 2.drop)
  13         fs="$(readlink "$vardir/snap-mount")"
  14         removes
  15         mount -vo remount,rw "$fs" || true
  16         ;;
  17 4.snap)
  18         removes
  19         mount -vo remount,ro "$4"
  20         ln -s -- "$3" "$vardir/snap-device"
  21         ln -s -- "$4" "$vardir/snap-mount"
  22         ;;
  23 *)
  24         cat >&2 <<'END'
  25 usage: .../remount snap VARDIR DEV MOUNT
  26        .../remount drop VARDIR
  27 END
  28         exit 1
  29         ;;
  30 esac