Shrinking (compressing) and restoring (decompressing) of data.

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32
votes
5answers
37k views

Clear unused space with zeros (ext3,ext4)

How to clear unused space with zeros ? (ext3,ext4) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like FSArchiver is looking for "used space" ...
25
votes
5answers
31k views

Which file compression software for linux offers the highest size reduction? [closed]

I do a ton of file compression. Most of the stuff I am compressing is just code, so I need to use loss less compression. I was wondering if there was anything that offers a better size reduction ...
11
votes
3answers
8k views

How can I view gzipped files in less without having to type zless?

I am using Ubuntu, and I would like to be able to type less compressed_text_file.gz and page the contents of the text file in uncompressed form. Is there a way to do this?
8
votes
6answers
280 views

Is there any program to provide a consistent interface across multiple archive types?

At the moment, if I download a compressed file, it could be any of a .tar.gz archive, a tar.bz2 arhive, a .zip archive or a .gz archive. And each time I do so, I have to remember what the command line ...
66
votes
7answers
46k views

How to XZ a directory with TAR using maximum compression?

So I need to compress a directory with max compression. How can I do it with xz? I mean I will need tar too because I can't compress a directory with only xz. Is there a oneliner to produce e.g. foo....
41
votes
5answers
34k views

Is it possible to mount a gzip compressed dd image on the fly?

I like create an image backup for the first time I'm backing up a system. After this first time I use rsync to do incremental backups. My usual image backup is as follows: Mount and zero out the ...
37
votes
5answers
41k views

How to uncompress zlib data in UNIX?

I have created zlib-compressed data in Python, like this: import zlib s = '...' z = zlib.compress(s) with open('/tmp/data', 'w') as f: f.write(z) (or one-liner in shell: echo -n '...' | python2 ...
12
votes
3answers
2k views

Universal extractors

With an increasing number of archive/compression file formats, is there a single free/open-source command line tool to rule them all? Perhaps something with a consistent / unified set of flags? (note ...
12
votes
2answers
11k views

How to extract files from uImage?

Buildroot is generating Images for an embedded device where they should run on. This is working very well. In those Images the rootfs is included. Due to some research I'd like to look into that ...
6
votes
1answer
4k views

Clear unused space with zeros (btrfs)

How to clear unused space with zeros ? (I am asking for tool for btrfs filesystem) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like ...
17
votes
3answers
3k views

Fastest way of working out uncompressed size of large GZIPPED file

Once a file is gzipped, is there a way of quickly querying it to say what the uncompressed file size is (without decompressing it), especially in cases where the uncompressed file is > 4GB in size. ...
11
votes
3answers
8k views

How do I compress files in-place?

I have a machine with 90% hard-disk usage. I want to compress its 500+ log files into a smaller new file. However, the hard disk is too small to keep both the original files and the compressed ones. ...
5
votes
3answers
12k views

Determine whether a particular file is compressed

How to know in Linux whether a particular file is compressed or not using a command?