domenica 17 maggio 2009

Unrar, tool di decompressione per i file in formato .rar

Maria Susana Diaz | 08:27 |
Unrar è il tool di decompressione per i file in formato 'rar', del popolare programma di compressione WINRAR usato sotto windows adesso anche disponibile anche per Linux.

Per decomprimere file RAR su Ubuntu bisogna installare alcuni pacchetti opzionali, quindi da terminale date un:

sudo apt-get install unrar

A questo punto per estrarre file compressi da interfaccia grafica basta semplicemente usare il normalissimo gestore di archivi (Tasto destro–>Estrai qui), perchè grazie a questi pacchetti sarà in grado di gestire quei file senza problemi.

Decomprimere un archivio autoestrante in formato .exe
L'archivio autoestraente risulta molto utile in situazioni dove chi riceve l'archivio non ha alcun tool di decompressione e l'unico modo è inviargli un archivio autoestraente in grado di autoestrarsi da solo. Anche se sotto linux il formato exe non è riconosciuto, possiamo comuque estrarlo utilizzando sempre l'opzione 'x'.

# unrar x nome_archivio.exe

Decomprimere un archivio protetto da password.
Nel caso in cui un archivio fosse protteto con password, unRAR è in grado di fornire in automatico un prompt per inserire la password.Quindi utilizzate sempre il comando 'unrar' con l'opzione 'x'.


Decomprimere e riassemblare parti di un archivio.
Qualche volta ci è capitato di scaricare per esempio archivi compressi del tipo 'file_part1.rar' 'file_part2.rar' e 'file_part3.rar'. Cosa fare? Niente di più facile, creare una cartella temporanea, esempio temp, copiarvi all'interno i tre file visti in questo esempio, e scompattare normalmente soltanto il primo archivio 'file_part1.rar'.

Le librerie di Unrar.

Qualche F.A.Q.:

What is a RAR file and how do to open RAR files?
A RAR archive is a "collection of files". Compression is used to make the archive file size smaller. A RAR archive is something like a ZIP archive, but the compression is usually better. The program WinRAR can create and extract RAR archives. For further information please visit the official RAR homepage.
If you want to extract ("open", "read") RAR archives, you may use a tool like WinRAR, WinZIP the free Aladdin Expander. These tools can be found at http://www.download.com.

What is a URARFileLib?
The URARFileLib (short name for UniquE RAR File Library, also called unrarlib) is a free library for C programmers to access RAR archives.

There is no way to create a RAR archive with the URARFileLib. When will you add a "create archive" function?
Probably never. The license of the free unrar source code prohibits making a tool that can create RAR compatible archives. Eugene Roshal spent a lot of time making RAR what it is today and RAR helps him to earn his livelihood. If you really need to create RAR archives form your application, I suggest contacting the author of RAR.

Which version of WinRAR should I use to create the RAR archives?
Currently, only the RAR 2.0 archive format is supported. Use WinRAR v2.9 (RAR 3.0 is introducing new compression algorithms which are not implemented yet). If you don't have this version of WinRAR, you can get it here.

Do you know that the license for the unrar sources from RARLab is not compatible with the GNU Public license?
Yes, this is true. But we have the permission from Eugene Roshal to release unrarlib 0.4.0 under GPL and unrarlib-license. Note: this doen't mean that RAR is free now or you can use the unrar source from RARlabs under GPL. You are just allowed to use UniquE RAR File Library version 0.4.0 (unrarlib 0.4.0) under GPL.

What about RAR 3 support?

RAR3 support is not scheduled. It would imply problems with the GPL license (RAR3 features a PPM based compression algorithm developed by Dmitry Shkarin plus some code by Eugeny Roshal).
If you need RAR3 support, check ftp.rarlabs.com for the original unrar source code and extract the needed code yourself.
Windows developers may have a look at Sebastian Schuberth's "arch::ifstream" library (requires the unrar.dll).

If YOU added RAR3 support and would like to share it with the 2000 monthly visitors of this page, so please let me know.

Update (12/2005): valuable hint by Jordi Burguet Castell: "Incidentally, I could get the source from ftp://ftp.rarlabs.com/rar/unrarsrc-3.5.4.tar.gz and easily compiled it with "make -f makefile.unix" as explained there (my system is a Debian unstable i386). Now I can finally unrar some rar3 files I had, which is what I really needed! Probably it is evident, but I thought it wasn't going to work.".


TiPI (Ti Potrebbe Interessare)

160x600    rotazione

weekend


LinuxLinks



GOOGLE+

LINKEDIN

Xtreme Download Manager, XDMAN Ubuntu, audio, Linux opera mini, browser internet Chromium Linux, Chrome, browsers tux collection, mascote Linux LibreCAD, Grafica, Disegno vim, editor, linux, ubuntu Ardour, audio, Ubuntu Unity, deskyop, Gnome, Ubuntu grafica 3d, Linux, Blender