nightly-backup.sh

Shall高级编程

#!/bin/bash
# nightly-backup.sh
# http://www.richardneill.org/source.php#nightly-backup-rsync
# Copyright (c) 2005 Richard Neill <[e-mail]>.
# This is Free Software licensed under the GNU GPL.
# ==> Included in ABS Guide with script author's kind permission.
# ==> (Thanks!)

#  This does a backup from the host computer to a locally connected
#+ firewire HDD using rsync and ssh.
#  It then rotates the backups.
#  Run it via cron every night at 5am.
#  This only backs up the home directory.
#  If ownerships (other than the user's) should be preserved,
#+ then run the rsync process as root (and re-instate the -o).
#  We save every day for 7 days, then every week for 4 weeks,
#+ then every month for 3 months.

#  See: http://www.mikerubel.org/computers/rsync_snapshots/
#+ for more explanation of the theory.
#  Save as: $HOME/bin/nightly-backup_firewire-hdd.sh

#  Known bugs:
#  ----------
#  i)  Ideally, we want to exclude ~/.tmp and the browser caches.

#  ii) If the user is sitting at the computer at 5am,
#+     and files are modified while the rsync is occurring,
#+     then the BACKUP_JUSTINCASE branch gets triggered.
#      To some extent, this is a 
#+     feature, but it also causes a "disk-space leak".





##### BEGIN CONFIGURATION SECTION ############################################
LOCAL_USER=rjn                # User whose home directory should be backed up.
MOUNT_POINT=/backup           # Mountpoint of backup drive.
                              # NO trailing slash!
                              # This must be unique (eg using a udev symlink)
SOURCE_DIR=/home/$LOCAL_USER  # NO trailing slash - it DOES matter to rsync.
BACKUP_DEST_DIR=$MOUNT_POINT/backup/`hostname -s`.${LOCAL_USER}.nightly_backup
DRY_RUN=false                 #If true, invoke rsync with -n, to do a dry run.
                              # Comment out or set to false for normal use.
VERBOSE=false                 # If true, make rsync verbose.
                              # Comment out or set to false otherwise.
COMPRESS=false                # If true, compress.
                              # Good for internet, bad on LAN.
                              # Comment out or set to false otherwise.

### Exit Codes ###
E_VARS_NOT_SET=64
E_COMMANDLINE=65
E_MOUNT_FAIL=70
E_NOSOURCEDIR=71
E_UNMOUNTED=72
E_BACKUP=73
##### END CONFIGURATION SECTION ##############################################


# Check that all the important variables have been set:
if [ -z "$LOCAL_USER" ] ||
   [ -z "$SOURCE_DIR" ] ||
   [ -z "$MOUNT_POINT" ]  ||
   [ -z "$BACKUP_DEST_DIR" ]
then
   echo 'One of the variables is not set! Edit the file: $0. BACKUP FAILED.'
   exit $E_VARS_NOT_SET
fi

if [ "$#" != 0 ]  # If command-line param(s) . . .
then              # Here document(ation).
  cat <<-ENDOFTEXT
    Automatic Nightly backup run from cron.
    Read the source for more details: $0
    The backup directory is $BACKUP_DEST_DIR .
    It will be created if necessary; initialisation is no longer required.

    WARNING: Contents of $BACKUP_DEST_DIR are rotated.
    Directories named 'backup.\$i' will eventually be DELETED.
    We keep backups from every day for 7 days (1-8),
    then every week for 4 weeks (9-12),
    then every month for 3 months (13-15).

    You may wish to add this to your crontab using 'crontab -e'
    #  Back up files: $SOURCE_DIR to $BACKUP_DEST_DIR
    #+ every night at 3:15 am
         15 03 * * * /home/$LOCAL_USER/bin/nightly-backup_firewire-hdd.sh

    Don't forget to verify the backups are working,
    especially if you don't read cron's mail!"
	ENDOFTEXT
   exit $E_COMMANDLINE
fi


# Parse the options.
# ==================

if [ "$DRY_RUN" == "true" ]; then
  DRY_RUN="-n"
  echo "WARNING:"
  echo "THIS IS A 'DRY RUN'!"
  echo "No data will actually be transferred!"
else
  DRY_RUN=""
fi

if [ "$VERBOSE" == "true" ]; then
  VERBOSE="-v"
else
  VERBOSE=""
fi

if [ "$COMPRESS" == "true" ]; then
  COMPRESS="-z"
else
  COMPRESS=""
fi


#  Every week (actually of 8 days) and every month,
#+ extra backups are preserved.
DAY_OF_MONTH=`date +%d`            # Day of month (01..31).
if [ $DAY_OF_MONTH = 01 ]; then    # First of month.
  MONTHSTART=true
elif [ $DAY_OF_MONTH = 08 \
    -o $DAY_OF_MONTH = 16 \
    -o $DAY_OF_MONTH = 24 ]; then
    # Day 8,16,24  (use 8, not 7 to better handle 31-day months)
      WEEKSTART=true
fi



#  Check that the HDD is mounted.
#  At least, check that *something* is mounted here!
#  We can use something unique to the device, rather than just guessing
#+ the scsi-id by having an appropriate udev rule in
#+ /etc/udev/rules.d/10-rules.local
#+ and by putting a relevant entry in /etc/fstab.
#  Eg: this udev rule:
# BUS="scsi", KERNEL="sd*", SYSFS{vendor}="WDC WD16",
# SYSFS{model}="00JB-00GVA0     ", NAME="%k", SYMLINK="lacie_1394d%n"

if mount | grep $MOUNT_POINT >/dev/null; then
  echo "Mount point $MOUNT_POINT is indeed mounted. OK"
else
  echo -n "Attempting to mount $MOUNT_POINT..."	
           # If it isn't mounted, try to mount it.
  sudo mount $MOUNT_POINT 2>/dev/null

  if mount | grep $MOUNT_POINT >/dev/null; then
    UNMOUNT_LATER=TRUE
    echo "OK"
    #  Note: Ensure that this is also unmounted
    #+ if we exit prematurely with failure.
  else
    echo "FAILED"
    echo -e "Nothing is mounted at $MOUNT_POINT. BACKUP FAILED!"
    exit $E_MOUNT_FAIL
  fi
fi


# Check that source dir exists and is readable.
if [ ! -r  $SOURCE_DIR ] ; then
  echo "$SOURCE_DIR does not exist, or cannot be read. BACKUP FAILED."
  exit $E_NOSOURCEDIR
fi


# Check that the backup directory structure is as it should be.
# If not, create it.
# Create the subdirectories.
# Note that backup.0 will be created as needed by rsync.

for ((i=1;i<=15;i++)); do
  if [ ! -d $BACKUP_DEST_DIR/backup.$i ]; then
    if /bin/mkdir -p $BACKUP_DEST_DIR/backup.$i ; then
    #  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  No [ ] test brackets. Why?
      echo "Warning: directory $BACKUP_DEST_DIR/backup.$i is missing,"
      echo "or was not initialised. (Re-)creating it."
    else
      echo "ERROR: directory $BACKUP_DEST_DIR/backup.$i"
      echo "is missing and could not be created."
    if  [ "$UNMOUNT_LATER" == "TRUE" ]; then
        # Before we exit, unmount the mount point if necessary.
        cd
	sudo umount $MOUNT_POINT &&
	echo "Unmounted $MOUNT_POINT again. Giving up."
    fi
      exit $E_UNMOUNTED
  fi
fi
done


#  Set the permission to 700 for security
#+ on an otherwise permissive multi-user system.
if ! /bin/chmod 700 $BACKUP_DEST_DIR ; then
  echo "ERROR: Could not set permissions on $BACKUP_DEST_DIR to 700."

  if  [ "$UNMOUNT_LATER" == "TRUE" ]; then
  # Before we exit, unmount the mount point if necessary.
     cd ; sudo umount $MOUNT_POINT \
     && echo "Unmounted $MOUNT_POINT again. Giving up."
  fi

  exit $E_UNMOUNTED
fi

# Create the symlink: current -> backup.1 if required.
# A failure here is not critical.
cd $BACKUP_DEST_DIR
if [ ! -h current ] ; then
  if ! /bin/ln -s backup.1 current ; then
    echo "WARNING: could not create symlink current -> backup.1"
  fi
fi


# Now, do the rsync.
echo "Now doing backup with rsync..."
echo "Source dir: $SOURCE_DIR"
echo -e "Backup destination dir: $BACKUP_DEST_DIR\n"


/usr/bin/rsync $DRY_RUN $VERBOSE -a -S --delete --modify-window=60 \
--link-dest=../backup.1 $SOURCE_DIR $BACKUP_DEST_DIR/backup.0/

#  Only warn, rather than exit if the rsync failed,
#+ since it may only be a minor problem.
#  E.g., if one file is not readable, rsync will fail.
#  This shouldn't prevent the rotation.
#  Not using, e.g., `date +%a`  since these directories
#+ are just full of links and don't consume *that much* space.

if [ $? != 0 ]; then
  BACKUP_JUSTINCASE=backup.`date +%F_%T`.justincase
  echo "WARNING: the rsync process did not entirely succeed."
  echo "Something might be wrong."
  echo "Saving an extra copy at: $BACKUP_JUSTINCASE"
  echo "WARNING: if this occurs regularly, a LOT of space will be consumed,"
  echo "even though these are just hard-links!"
fi

# Save a readme in the backup parent directory.
# Save another one in the recent subdirectory.
echo "Backup of $SOURCE_DIR on `hostname` was last run on \
`date`" > $BACKUP_DEST_DIR/README.txt
echo "This backup of $SOURCE_DIR on `hostname` was created on \
`date`" > $BACKUP_DEST_DIR/backup.0/README.txt

# If we are not in a dry run, rotate the backups.
[ -z "$DRY_RUN" ] &&

  #  Check how full the backup disk is.
  #  Warn if 90%. if 98% or more, we'll probably fail, so give up.
  #  (Note: df can output to more than one line.)
  #  We test this here, rather than before
  #+ so that rsync may possibly have a chance.
  DISK_FULL_PERCENT=`/bin/df $BACKUP_DEST_DIR |
  tr "\n" ' ' | awk '{print $12}' | grep -oE [0-9]+ `
  echo "Disk space check on backup partition \
  $MOUNT_POINT $DISK_FULL_PERCENT% full."
  if [ $DISK_FULL_PERCENT -gt 90 ]; then
    echo "Warning: Disk is greater than 90% full."
  fi
  if [ $DISK_FULL_PERCENT -gt 98 ]; then
    echo "Error: Disk is full! Giving up."
      if  [ "$UNMOUNT_LATER" == "TRUE" ]; then
        # Before we exit, unmount the mount point if necessary.
        cd; sudo umount $MOUNT_POINT &&
        echo "Unmounted $MOUNT_POINT again. Giving up."
      fi
    exit $E_UNMOUNTED
  fi


 # Create an extra backup.
 # If this copy fails, give up.
 if [ -n "$BACKUP_JUSTINCASE" ]; then
   if ! /bin/cp -al $BACKUP_DEST_DIR/backup.0 \
      $BACKUP_DEST_DIR/$BACKUP_JUSTINCASE
   then
     echo "ERROR: Failed to create extra copy \
     $BACKUP_DEST_DIR/$BACKUP_JUSTINCASE"
     if  [ "$UNMOUNT_LATER" == "TRUE" ]; then
       # Before we exit, unmount the mount point if necessary.
       cd ;sudo umount $MOUNT_POINT &&
       echo "Unmounted $MOUNT_POINT again. Giving up."
     fi
     exit $E_UNMOUNTED
   fi
 fi


 # At start of month, rotate the oldest 8.
 if [ "$MONTHSTART" == "true" ]; then
   echo -e "\nStart of month. \
   Removing oldest backup: $BACKUP_DEST_DIR/backup.15"  &&
   /bin/rm -rf  $BACKUP_DEST_DIR/backup.15  &&
   echo "Rotating monthly,weekly backups: \
   $BACKUP_DEST_DIR/backup.[8-14] -> $BACKUP_DEST_DIR/backup.[9-15]"  &&
     /bin/mv $BACKUP_DEST_DIR/backup.14 $BACKUP_DEST_DIR/backup.15  &&
     /bin/mv $BACKUP_DEST_DIR/backup.13 $BACKUP_DEST_DIR/backup.14  &&
     /bin/mv $BACKUP_DEST_DIR/backup.12 $BACKUP_DEST_DIR/backup.13  &&
     /bin/mv $BACKUP_DEST_DIR/backup.11 $BACKUP_DEST_DIR/backup.12  &&
     /bin/mv $BACKUP_DEST_DIR/backup.10 $BACKUP_DEST_DIR/backup.11  &&
     /bin/mv $BACKUP_DEST_DIR/backup.9 $BACKUP_DEST_DIR/backup.10  &&
     /bin/mv $BACKUP_DEST_DIR/backup.8 $BACKUP_DEST_DIR/backup.9

 # At start of week, rotate the second-oldest 4.
 elif [ "$WEEKSTART" == "true" ]; then
   echo -e "\nStart of week. \
   Removing oldest weekly backup: $BACKUP_DEST_DIR/backup.12"  &&
   /bin/rm -rf  $BACKUP_DEST_DIR/backup.12  &&

   echo "Rotating weekly backups: \
   $BACKUP_DEST_DIR/backup.[8-11] -> $BACKUP_DEST_DIR/backup.[9-12]"  &&
     /bin/mv $BACKUP_DEST_DIR/backup.11 $BACKUP_DEST_DIR/backup.12  &&
     /bin/mv $BACKUP_DEST_DIR/backup.10 $BACKUP_DEST_DIR/backup.11  &&
     /bin/mv $BACKUP_DEST_DIR/backup.9 $BACKUP_DEST_DIR/backup.10  &&
     /bin/mv $BACKUP_DEST_DIR/backup.8 $BACKUP_DEST_DIR/backup.9

 else
   echo -e "\nRemoving oldest daily backup: $BACKUP_DEST_DIR/backup.8"  &&
     /bin/rm -rf  $BACKUP_DEST_DIR/backup.8

 fi  &&

 # Every day, rotate the newest 8.
 echo "Rotating daily backups: \
 $BACKUP_DEST_DIR/backup.[1-7] -> $BACKUP_DEST_DIR/backup.[2-8]"  &&
     /bin/mv $BACKUP_DEST_DIR/backup.7 $BACKUP_DEST_DIR/backup.8  &&
     /bin/mv $BACKUP_DEST_DIR/backup.6 $BACKUP_DEST_DIR/backup.7  &&
     /bin/mv $BACKUP_DEST_DIR/backup.5 $BACKUP_DEST_DIR/backup.6  &&
     /bin/mv $BACKUP_DEST_DIR/backup.4 $BACKUP_DEST_DIR/backup.5  &&
     /bin/mv $BACKUP_DEST_DIR/backup.3 $BACKUP_DEST_DIR/backup.4  &&
     /bin/mv $BACKUP_DEST_DIR/backup.2 $BACKUP_DEST_DIR/backup.3  &&
     /bin/mv $BACKUP_DEST_DIR/backup.1 $BACKUP_DEST_DIR/backup.2  &&
     /bin/mv $BACKUP_DEST_DIR/backup.0 $BACKUP_DEST_DIR/backup.1  &&

 SUCCESS=true


if  [ "$UNMOUNT_LATER" == "TRUE" ]; then
  # Unmount the mount point if it wasn't mounted to begin with.
  cd ; sudo umount $MOUNT_POINT && echo "Unmounted $MOUNT_POINT again."
fi


if [ "$SUCCESS" == "true" ]; then
  echo 'SUCCESS!'
  exit 0
fi

# Should have already exited if backup worked.
echo 'BACKUP FAILED! Is this just a dry run? Is the disk full?) '
exit $E_BACKUP