Extract Deb files from command line

Debian and its derivatives use the .deb format to distribute their packages. To extract them, use ar – Yes, the very program we programmers use to make static libraries.

ar x sudo_1.6.9p17-2_i386.deb

Or we can directly extract things from data.tar.gz contained in the .deb file:

ar p sudo_1.6.9p17-2_i386.deb data.tar.gz | tar -xzf -

No longer a user of Debian GNU/Linux, I still have to remember how to extract .deb files. I frequently need to cross-compile a 64-bit version of my program on a 32-bit system, and vice versa; but I don’t want to cross-compile by myself so many libraries on which my program depends. Instead, I find it a good idea to download a right .deb file from the Debian Packages Repository and pick out the .so files.

Tags: compression, Debian, Gentoo, Linux

liblzmadec sucks

Both the executable lzma and the library liblzmadec are included in the package lzma-utils (in Gentoo).

If I compress a file a.txt like this:

lzma a.txt

then liblzmadec can decompress a.txt.lzma perfectly.

However, if I compress it like this:

lzma < a.txt > a.txt.lzma

Then liblzmadec fails.

LZMA is a compression algorithm whose application rate has been rapidly growing in the past year. In most cases, it has significantly better compression ratio compressed to bzip2 and gzip, and decompresses significantly faster. However, its compression process is extremely slow (probably 10 times longer the time than bzip2).

One of the algorithms supported by 7zip is LZMA. In Linux we usually use LZMA Utils instead.

GNU provided the tarball of some versions of coreutils in LZMA (in addition to the traditional GZIP), although they have recently switched to xz.

Tags: compression, dev