dar est un utilitaire sous linux permettant de réaliser des sauvegardes simple avec quelques fonctions avancées comme :

• la gestion des sauvegardes complètes et incrémentales
• le support du chiffrement des données
• la compression des données

Cette page décrit comment l'utiliser ponctuellement ou de manière automatisée.

Installer le paquet :

• dar

Voici le résultat de l'aide intégrée à dar.

# dar -h
usage: dar [ -c | -x | -d | -t | -l | -C | -+ ] [<path>/]<basename> [options...]
       dar -h
       dar -V

Commands are:
   -c  creates an archive
   -x  extracts files from the archive
   -d  compares the archive with the existing filesystem
   -t  tests the archive integrity
   -l  lists the contents of the archive
   -C  isolates the catalogue from an archive
   -+  merge two archives / create a sub archive

   -h  displays this help information
   -V  displays version information

Common options:
   -v              verbose output
   -q              suppress final statistics report
   -vs             display skipped files
   -R <path>       filesystem root directory (current dir by default)
   -X <mask>       files to exclude from the operation (none by default)
   -I <mask>       files to include in the operation (all by default)
   -P <path>       subdirectory to exclude from the operation
   -g <path>       subdirectory to include in the operation
   -[ <filename>   filename contains a list of files to include
   -] <path>       filename contains a list of files to exclude
   -n              don't overwrite files
   -w              don't warn before overwriting files
   -wa             don't warn before overwriting and removing files
   -b              ring the terminal bell when user action is required
   -O[ignore-owner | mtime | inode-type] do not consider user and group
                   ownership
   -H [N]          ignore shift in dates of an exact number of hours
   -E <string>     command to execute between slices
   -F <string>     same as -E but for the archive of reference
   -u <mask>       mask to ignore certain EA
   -U <mask>       mask to allow certain EA
   -K <string>     use <string> as key to encrypt/decrypt
   -J <string>     same as -K but it does concern the archive of reference
   -# <integer>    encryption block size
   -* <integer>    same as -# but for archive of reference
   -B <filename>   read options from given file
   -N              do not read ~/.darrc nor /etc/darrc configuration file
   -e              dry run, fake execution, nothing is produced
   -Q              suppress the initial warning when not launched from a tty
   -aa             do not try to preserve atime of file open for reading.
   -ac             do not try to preserve ctime (default behavior).
   -am             set ordered mode for all filters
   -an             the masks that follow are now case insensitive
   -acase          the masks that follow are now case sensitive
   -ar             set the following masks to be regex expressions
   -ag             set the following masks to be glob expressions
   -j              ask user what to do when memory is exhausted

Saving / Isolation / merging options (to use with -c, -C or -+):
   -A [path/]<basename> archive to take as reference
   -@ [path/]<basename> auxiliary archive of reference for merging
   -$ <string>     encryption key for auxiliary archive
   -~ <string>     command between slices of the auxiliary archive
   -z [level]      compress data in archive using gzip algorithm
   -y [level]      compress data in archive using bzip2 algorithm.
   -s <integer>    split the archive in several files of size <integer>
   -S <integer>    first file size (if different from following ones)
   -aSI            slice size suffixes k, M, T, G, etc. are power of 10
   -abinary        slice size suffixes k, M, T, G, etc. are power of 2
   -p              pauses before writing to a new file
   -D              excluded directories are stored as empty directories
   -Z <mask>       do not compress the matching filenames
   -Y <mask>       do only compress the matching filenames
   -m <number>     do not compress file smaller than <number>
   --nodump        do not backup, files having the nodump 'd' flag set
   -G [path/]<basename> Do on-fly catalogue isolation of the resulting archive
   -M              stay in the same filesystem while scanning directories
   -,              ignore directories that follow the Directory Tagging
                   Standard

Restoring options (to use with -x) :
   -k              do not remove files destroyed since the reference backup
   -r              do not restore file older than those on filesystem
   -f              do not restore directory structure

Reading options (to use with -x, -d, -t, -l, -A)
   -i <named pipe> pipe to use instead of std input to read data from dar_slave
   -o <named pipe> pipe to use instead of std output to orders dar_slave

Listing options (to use with -l):
   -T              tree output format
   -as             only list files saved in the archive


Type "man dar" for more details and for all available options.

Commençons par un simple sauvegarde de /home :

dar -v -c home -R / -g home

Quelques détails des options :

• -c home : indique que nous voulons créer la sauvegarde home.dar
• -R / : défini le chemin relatif pour la sauvegarde, sinon le répertoire actuel est utilisé
• -g home : indique le répertoire à sauvegarder, celui-ci est relatif à l'option -R
• -v : active le mode verbeux

Exemple d'exécution :

# dar -v -c home -R / -g home
Adding file to archive: /home
Adding file to archive: /home/matthieu
Adding file to archive: /home/matthieu/.bashrc
Adding file to archive: /home/matthieu/.bash_logout
Adding file to archive: /home/matthieu/.profile
....
....
Writing archive contents...


 --------------------------------------------
 56 inode(s) saved
 with 0 hard link(s) recorded
 0 inode(s) changed at the moment of the backup
 0 inode(s) not saved (no inode/file change)
 0 inode(s) failed to save (filesystem error)
 28 inode(s) ignored (excluded by filters)
 0 inode(s) recorded as deleted from reference backup
 --------------------------------------------
 Total number of inodes considered: 84
 --------------------------------------------
 EA saved for 0 inode(s)
 --------------------------------------------

Pour visualiser la sauvegarde, il faut utiliser l'option -l :

dar -l home

Exemple :

[data ][ EA  ][compr] | permission | user  | group | size  |          date                 |    filename
----------------------+------------+-------+-------+-------+-------------------------------+------------
[Saved]       [-----]   drwxr-xr-x   0  root    0       Sun Mar  7 15:08:58 2010        home
[Saved]       [-----]   drwxr-xr-x   matthieu   matthieu        0       Fri Mar  5 21:48:35 2010        home/matthieu
[Saved]       [     ]   -rw-r--r--   matthieu   matthieu        3116    Fri Mar  5 21:48:35 2010        home/matthieu/.bashrc
[Saved]       [     ]   -rw-r--r--   matthieu   matthieu        220     Fri Mar  5 21:48:35 2010        home/matthieu/.bash_logout
[Saved]       [     ]   -rw-r--r--   matthieu   matthieu        675     Fri Mar  5 21:48:35 2010        home/matthieu/.profile
...

#!/bin/sh

# Dar backup script
# Matthieu Bouthors
# http://www.bouthors.fr
# licence GPLv2

# location of files
config_dir=/home/scripts
# temporary file
run_file=archive_gandalf_running
# dar options (DCF format)
dar_options=gandalf.dcf
# file that save the last full backup
last_backup_file=last_dar
# destination folder
archive_dir=/data/backup


case "$1" in
  full)
        if [ -e "$config_dir/$run_file" ]
        then
                echo archive already running
        exit 1
        fi
        touch "$config_dir/$run_file"

        archive_file="full_`date +%Y%m%d_%H%M%S`"
        echo $archive_file
        /usr/bin/dar -c $archive_dir/$archive_file -B $config_dir/$dar_options
        if [ $? -eq 0 ]
        then
                echo "$archive_dir/$archive_file" > $config_dir/$last_backup_file
                rm -f "$config_dir/$run_file"
                exit 0
        fi
        rm -f "$config_dir/$run_file"
        exit $?
        ;;
  inc)

        if [ ! -e "$config_dir/$last_backup_file" ]
        then
                echo no previous dar
        exit 1
        fi

        old_dar=`cat $config_dir/$last_backup_file`
        echo reference dar : $old_dar

        if [ ! -e "$old_dar.1.dar" ]
        then
                echo previous dar not found
        exit 1
        fi

        if [ -e "$config_dir/$run_file" ]
        then
                echo archive already running
        exit 1
        fi
        touch "$config_dir/$run_file"

        archive_file="inc_`date +%Y%m%d_%H%M%S`"
        echo $archive_file
        /usr/bin/dar -c $archive_dir/$archive_file -A $old_dar -B $config_dir/$dar_options
        if [ $? -eq 0 ]
        then
                rm -f "$config_dir/$run_file"
                exit 0
        fi
        rm -f "$config_dir/$run_file"
        exit $?
        ;;

  kill)
        killall dar
        rm -f "$config_dir/$run_file"
        exit 0
        ;;
  *)
        echo "option : full, inc"
        exit 1
esac
exit 0

Voici un script permettant de supprimer les sauvegardes trop vielles

#!/bin/sh

# Dar cleanup script
# Matthieu Bouthors
# http://www.bouthors.fr
# licence GPLv2

#folder to watch :
watch_folder=/data/backup/

# delete inc files older than inc_keep days :
inc_keep=60
# delete full files older than full_keep days :
full_keep=180

now=`date +%s`
limit_keep=$(($now-($inc_keep*86400)))

for filename in `ls $watch_folder/inc*.dar`
do
        find_date_text=`expr match $filename '.*/inc_\([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\)_'`
        date_file=`date -d $find_date_text +%s`
        if [ $date_file -lt $limit_keep ]
        then
                /bin/rm -vf $filename
        fi
done


limit_keep=$(($now-($full_keep*86400)))


for filename in `ls $watch_folder/full*.dar`
do
        find_date_text=`expr match $filename '.*/full_\([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\)_'`
        date_file=`date -d $find_date_text +%s`
        if [ $date_file -lt $limit_keep ]
        then
               /bin/rm -vf $filename
        fi
done

• http://dar.linux.free.fr/
• http://dar.linux.free.fr/doc/samples/index.html