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I created a big tar.gz file, following this guide. It is a daily backup file.

My computer has 3 GB of RAM and is running Windows 7. My biggest archive is 183 GB, containing pictures and documents.

The backup is quite useless since I can't open it and extract. Every time I try, my computer always runs out of memory (using 7-zip).

Has anybody had the same problems?

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Does it run out of RAM or disk space? What is the error message? – gronostaj May 21 '13 at 9:13

You need to open the file using something that reads and processes it as a stream, rather than trying to read the whole file into memory.

Try installing Cygwin and managing the file using its command-line tools; for example

$ tar zxf my-big-file.tar.gz something/I/want.doc

will extract one file from your archive.

As a Unix guy, naturally I offer a Unix-like solution :-)

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Installing Cygwin can be daunting for Windows users. An alternative would be to boot from a Linux LiveCD and run the tar command in that environment, no need to install anything that way. An alternate command in the Linux environment would be zcat my-big-file.tar.gz | tar xvf - something/I/want.doc. You can do zcat my-big-file.tar.gz | tar tvf - | more to list the files and see the correct path names first. – Jonathan Ben-Avraham May 21 '13 at 9:39
Fair comment -- thanks :) – Flup May 21 '13 at 9:54
@JonathanBen-Avraham - Its only daunting if you don't read the instructions. – Ramhound May 21 '13 at 11:22
Cygwin is not required. Tar is available via the GNU Win32 project – FSMaxB May 21 '13 at 17:33

Cygwin - as sugested - is an overkill. You can try to use which is a commandline tool and doesn't require installation (just unzip).

Then you can addapt suggested command:

tar xzf backup.tar.gz folder/file_you_want.txt

x - extract
z - compressed with GZ
f - file to extract

To work with tartool:

TarTool.exe backup.tar.gz /destination/

Unfortunately tartool doesn't allow to pick which file you want.

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Easy to use and working solution, thanks Chris – kubusz Nov 2 '15 at 11:09

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