Ceci n’est pas une pipe

Non dovrebbe. Ma può senz’altro succedere che si cancelli un file per errore e lo si voglia recuperare. Ci sono svariati tool a pagamento per effettuare questo tipo di operazione su filesystem FAT32 e NTFS sotto Windows. Anche il nostro pinguino offre più di uno strumento simile per recuperare file cancellati su filesystem EXT3. Uno fra questi è ext3birra, un programma per Linux il cui nome inconfondibilmente italico deriva dal nickname del programmatore che l’ha ideato.

Da quanto si legge sul sito ufficiale del progetto, questo utilissimo programma è stato scritto in soli 5 giorni e permette di recuperare solo file eliminati recentemente (entro le 24 ore).

Ecco come utilizzare il s/w:

• scaricare il programma da questo indirizzo
• estrarre i file con il consueto comando:
  tar -jxvf ext3birra*.tar.bz2
• spostarsi nella cartella così creata e lanciare il comando:
  make && make install
• terminata la compilazione, per usare ext3birra è sufficiente lanciare il comando:
  ext3birra [device] [output directory]

Ecco ad esempio come si possono recuperare i files precedentemente eliminati dalla partizione sda1, ripristinandoli nella directory temporanea /tmp/recupero_dati/:

ext3birra /dev/sda1 /tmp/recupero_dati/

Questa è stata una settimana molto, molto dura… ma non posso certo permettere che si concluda senza avere messo online almeno una piccola, miserabile, insignificante tip! Quindi, per fare le cose al volo, vi dico come effettuo la sincronizzazione di un sito Internet che ho elaborato in locale con la copia che è pubblicata nella directory di un certo spazio FTP.

Premetto che questo non è il modo in cui lavoro normalmente: da buon figlio degli anni ‘70 io modifico il codice direttamente online, non in produzione, ma online (bash). Questa settimana mi è capitato però di dover mettere mano al sito Internet di un cliente che ha messo a mia disposizione solo ed esclusivamente il suo account FTP. Quindi ho cominciato a sviluppare una copia locale del suo sito internet e tengo sincronizzata la versione online con un solo, semplice, meraviglioso comando:

lftp -u 'username,password‘ ftp.mydomain.com -e “set ftp:ssl-protect-data true;mirror –reverse /home/ivan/test test; exit

In altre parole:

• username: il nome utente dell’account FTP
• password: la password associata al nome utente dell’account FTP
• ftp.mydomain.com: la host dell’account FTP
• /home/ivan/test: la cartella locale (senza slash finale)
• test: la cartella remota (ovvero quella dove si trova pubblicato il sito Internet)

Da notare l’opzione “set ftp:ssl-protect-data true” che protegge l’autenticazione FTP mediante ssl e l’opzione “mirror –reverse” che permette di sincronizzare in upload anziché in download.

Inutile dire che con lo stesso comando si può mantenere un backup remoto di una directory locale, anche se per cose di questo tipo è consigliabile l’utilizzo di `rsync` che fa tutto attraverso una connessione `ssh`.

Niente di più, niente di meno. Buon week end!

Riporto qui integralmente la pagina che contiene gli esempi pubblicati sul sito ufficiale del progetto rdiff-backup. Non escludo di provvedere ad una sua progressiva traduzione, nei prossimi giorni, tempo permettendo.

rdiff-backup examples

Sections

• Backing up
• Restoring
• Deleting older files
• File selection with include/exclude options
• Getting information about the backup directory
• Miscellaneous other commands

Backing up

• Simplest case—backup local directory foo to local directory bar. bar will end up a copy of foo, except it will contain the directory foo/rdiff-backup-data, which will allow rdiff-backup to restore previous states.
  rdiff-backup foo bar
• Simple remote case—backup directory /some/local-dir to the directory /whatever/remote-dir on the machine hostname.net. It uses ssh to open the necessary pipe to the remote copy of rdiff-backup. Just like the above except one directory is on a remote computer.
  rdiff-backup /some/local-dir hostname.net::/whatever/remote-dir
• This time the source directory is remote and the destination is local. Also, we have specified the username on the remote host (by default ssh will attempt to log you in with the same username you have on the local host).
  rdiff-backup user@hostname.net::/remote-dir local-dir
• It is even possible for both the source and destination directories to be on other machines. Below we have also added the -v5 switch for greater verbosity (verbosity settings go from 0 to 9, with 3 as the default), and the –print-statistics switch so some statistics will be displayed at the end (even without this switch, the statistics will still be saved in the rdiff-backup-data directory).
  rdiff-backup -v5 --print-statistics user1@host1::/source-dir user2@host2::/dest-dir

Restoring

• Suppose earlier we have run rdiff-backup foo bar, with both foo and bar local. We accidentally deleted foo/dir and now want to restore it from bar/dir.
  cp -a bar/dir foo/dirThat’s right, since rdiff-backup makes a mirror, we can retrieve files using standard commands like cp.
• For the rest of the examples in the section, we will assume that the user has backed up with the command rdiff-backup local-dir host.net::/remote-dir. Of course, in all these examples it would be equally possible to have the source being remote and the backup directory local.In this case we can’t use cp to copying host.net::remote-dir/file to local-dir/file because they are on different machines. We can get rdiff-backup to restore the current version of that file using either of these::
  rdiff-backup --restore-as-of now host.net::/remote-dir/file local-dir/file
rdiff-backup -r now host.net::/remote-dir/file local-dir/fileThe –restore-as-of (or -r for short) switch tells rdiff-backup to restore instead of back up, and the now option indicates the current time.
• But the main advantage of rdiff-backup is that it keeps version history. This command restores host.net::/remote-dir/file as it was 10 days ago into a new location /tmp/file.
  rdiff-backup -r 10D host.net::/remote-dir/file /tmp/fileOther acceptable time strings include 5m4s (5 minutes and 4 seconds) and 2002-03-05 (March 5th, 2002). For more information, see the TIME FORMATS section of the manual page.
• Finally, we can use rdiff-backup to restore directory from an increment file. Increment files are stored in host.net::/remote-dir/rdiff-backup-data/increments and hold the previous versions of changed files. If you specify one directly:
  rdiff-backup host.net::/remote-dir/rdiff-backup-data/increments/file.2003-03-05T12:21:41-07:00.diff.gz local-dir/filerdiff-backup will tell from the filename that it is an rdiff-backup increment file and thus enter restore mode. Above the restored version is written to local-dir/file.

Deleting older files

Although rdiff-backup tries to save space by only storing file differences, eventually space may run out in the destination directory. rdiff-backup’s –remove-older-than mode can be used to delete older increments.

This section assumes that rdiff-backup has been used in the past to back up to host.net::/remote-dir, but all commands would work locally too, if the hostname were ommitted.

• This commands deletes all information concerning file versions which have not been current for 2 weeks:
  rdiff-backup --remove-older-than 2W host.net::/remote-dirNote that an existing file which hasn’t changed for a year will still be preserved. But a file which was deleted 15 days ago cannot be restored after this command is run.
• As when restoring, there are a variety of ways to specify the time. The 20B below tells rdiff-backup to only preserve information from the last 20 rdiff-backup sessions. (nnB syntax is only available in versions after 0.13.1.)
  rdiff-backup --remove-older-than 20B host.net::/remote-dir

File selection with include/exclude options

Sometimes you don’t want to back up all files. The various –include and –exclude options can be used to select exactly which files to back up. See the man page for a list of all the options and their definitions.

• In this example we exclude /mnt/backup to avoid an infinite loop.
  rdiff-backup --exclude /mnt/backup / /mnt/backup(Actually rdiff-backup can automatically detect simple loops like the one above.) This is just an example, in reality it would be important to exclude /proc as well.
• This example is more realistic. We have excluded /proc, /tmp, and /mnt. /proc in particular should never be backed up. Also, the source directory happens to be remote.
  rdiff-backup --exclude /tmp --exclude /mnt --exclude /proc user@host.net::/ /backup/host.net
• Multiple include and exclude options take precedence in the order they are given. The following command would back up /usr/local/bin but not /usr/bin.
  rdiff-backup --include /usr/local --exclude /usr / host.net::/backup
• rdiff-backup uses rsync-like wildcards, where ** matches any path and * matches any path without a / in it. Thus this command:
  rdiff-backup --include /usr/local --include /var --exclude '**' / /backupbacks up only the /usr/local and /var directories. The single quotes ” are not part of rdiff-backup and are only used because many shells will expand **.
• Here is a more complicated example:
  rdiff-backup --include '**txt' --exclude /usr/local/games --include /usr/local --exclude /usr --exclude /backup --exclude /proc / /backupThe above command will back up any file ending in txt, even /usr/local/games/pong/scores.txt because that include has highest precedence. The contents of the directory /usr/local/bin will get backed up, but not /usr/share or /usr/local/games/pong.
• rdiff-backup can also accept a list of files to be backed up. If the file include-list contains these two lines:
  /var
/usr/bin/gzipThen this command:
  rdiff-backup --include-filelist include-list --exclude '**' / /backup
  would only back up the files /var, /usr, /usr/bin, and /usr/bin/gzip, but not /var/log or /usr/bin/gunzip. Note that this differs from the –include option, since –include /var would also match /var/log.
• The same file list can both include and exclude files. If we create a file called include-list that contains these lines:
  **txt
- /usr/local/games
/usr/local
- /usr
- /backup
- /proc
  Then the following command will do exactly the same thing as the complicated example two above.
  rdiff-backup --include-globbing-filelist include-list / /backup
  Above we have used –include-globbing-filelist instead of –include-filelist so that the lines would be interpreted as if they were specified on the command line. Otherwise, for instance, **txt would be considered the name of a file, not a globbing string.

Getting information about the backup directory

The following examples assume that you have run rdiff-backup in-dir out-dir in the past.

• This command finds all new or old files which contain the string frobniz.
  find out-dir -name '*frobniz*'
  rdiff-backup doesn’t obscure the names of files at all, so often using traditional tools work well.
• Either of these equivalent commands lists the times of the available versions of the file out-dir/file. It may be useful if you need to restore an older version of in-dir/file but aren’t sure which one.
  rdiff-backup --list-increments out-dir/file
rdiff-backup -l out-dir/file
• The following command lists all the files under out-dir/subdir which has changed in the last 5 days.
  rdiff-backup --list-changed-since 5D out-dir/subdir
• This command lists all the files that were present in out-dir/subdir 5 days ago. This includes files that have not changed recently as well as those that have been deleted in the last 5 days.
  rdiff-backup --list-at-time 5D out-dir/subdir
• The first command below compares the current files in out-dir (which is on a remote computer) with the files in in-dir, displaying which ones have changed. The second command is similar but compares in-dir to out-dir as it was 2 weeks ago.
  rdiff-backup --compare in-dir user@host::out-dir
rdiff-backup --compare-at-time 2W in-dir user@host::out-dir
• rdiff-backup writes one statistics file per session to the out-dir/rdiff-backup-data directory. An average of the files can be displayed using the –calculate-average option and specifying the statistics files to use.
  rdiff-backup --calculate-average out-dir/rdiff-backup-data/session_statistics*

Miscellaneous other commands

• If you are having problems connecting to a remote host, the –test-server command may be useful. This command simply verifies that there is a working rdiff-backup server on the remote side.
  rdiff-backup --test-server hostname.net::/ignored

Fonte: http://rdiff-backup.nongnu.org

Capita a tutti di dover programmare un backup periodico da un server ad un altro. Immaginiamo di volere effettuare ogni giorno ad una certa ora la copia completa di tutti i file contenuti in una certa directory da un server (che chiameremo A) ad un altro (che chiameremo B). Una soluzione semplice consiste nel programmare la sincronizzazione da remoto mediante il programma `rsync`. Il programma verrà lanciato dal server B, in maniera tale che il server A subisca passivamente il backup - in forma di prelievo di dati - senza possibili conseguenze gravi. Leggi il resto »

Si trova ancora in circolazione software che affida il backup dei propri archivi di dati a dispositivi DAT (Digital Audio Tape). Di norma, software di questo genere include tutti gli strumenti necessari per effettuare e ripristinare i backup, ma capita a volte di avere bisogno di effettuare le stesse operazioni lavorando direttamente sugli archivi di dati, senza - in altre parole - passare necessariamente attraverso il software che li ha generati. Leggi il resto »