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191 lines
4.3 KiB
Markdown
191 lines
4.3 KiB
Markdown
pixz
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====
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[](https://travis-ci.org/vasi/pixz)
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Pixz (pronounced *pixie*) is a parallel, indexing version of `xz`.
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Repository: https://github.com/vasi/pixz
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Downloads: https://github.com/vasi/pixz/releases
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pixz vs xz
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----------
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The existing [XZ Utils](http://tukaani.org/xz/) provide great compression in the `.xz` file format,
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but they produce just one big block of compressed data. Pixz instead produces a collection of
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smaller blocks which makes random access to the original data possible. This is especially useful
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for large tarballs.
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### Differences to xz
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- `pixz` automatically indexes tarballs during compression (unless the `-t` argument is used)
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- `pixz` supports parallel decompression, which `xz` does not
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- `pixz` defaults to using all available CPU cores, while `xz` defaults to using only one core
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- `pixz` provides `-i` and `-o` command line options to specify input and output file
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- `pixz` does not need the command line option `-z` (or `--compress`). Instead, it compresses by default, and decompresses if `-d` is passed.
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- `pixz` uses different logic to decide whether to use stdin/stdout. `pixz somefile` will always output to another file, while `pixz` with no filenames will always use stdin/stdout. There's no `-c` argument to explicitly request stdout.
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- Some other flags mean different things for `pixz` and `xz`, including `-f`, `-l`, `-q` and `-t`. Please read the manpages for more detail on these.
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Building pixz
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-------------
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General help about the building process's configuration step can be acquired via:
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```
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./configure --help
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```
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### Dependencies
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- pthreads
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- liblzma 4.999.9-beta-212 or later (from the xz distribution)
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- libarchive 2.8 or later
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- AsciiDoc to generate the man page
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### Build from Release Tarball
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```
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./configure
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make
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make install
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```
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You many need `sudo` permissions to run `make install`.
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### Build from GitHub
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```
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git clone https://github.com/vasi/pixz.git
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cd pixz
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./autogen.sh
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./configure
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make
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make install
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```
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You many need `sudo` permissions to run `make install`.
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Usage
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-----
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### Single Files
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Compress a single file (no tarball, just compression), multi-core:
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pixz bar bar.xz
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Decompress it, multi-core:
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pixz -d bar.xz bar
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### Tarballs
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Compress and index a tarball, multi-core:
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pixz foo.tar foo.tpxz
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Very quickly list the contents of the compressed tarball:
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pixz -l foo.tpxz
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Decompress the tarball, multi-core:
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pixz -d foo.tpxz foo.tar
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Very quickly extract a single file, multi-core, also verifies that contents match index:
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pixz -x dir/file < foo.tpxz | tar x
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Create a tarball using pixz for multi-core compression:
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tar -Ipixz -cf foo.tpxz foo/
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### Specifying Input and Output
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These are the same (also work for `-x`, `-d` and `-l` as well):
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pixz foo.tar foo.tpxz
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pixz < foo.tar > foo.tpxz
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pixz -i foo.tar -o foo.tpxz
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Extract the files from `foo.tpxz` into `foo.tar`:
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pixz -x -i foo.tpxz -o foo.tar file1 file2 ...
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Compress to `foo.tpxz`, removing the original:
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pixz foo.tar
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Extract to `foo.tar`, removing the original:
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pixz -d foo.tpxz
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### Other Flags
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Faster, worse compression:
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pixz -1 foo.tar
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Better, slower compression:
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pixz -9 foo.tar
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Use exactly 2 threads:
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pixz -p 2 foo.tar
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Compress, but do not treat it as a tarball, i.e. do not index it:
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pixz -t foo.tar
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Decompress, but do not check that contents match index:
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pixz -d -t foo.tpxz
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List the xz blocks instead of files:
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pixz -l -t foo.tpxz
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For even more tuning flags, check the manual page:
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man pixz
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Comparison to other Tools
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-------------------------
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### plzip
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- about equally complex and efficient
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- lzip format seems less-used
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- version 1 is theoretically indexable, I think
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### ChopZip
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- written in Python, much simpler
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- more flexible, supports arbitrary compression programs
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- uses streams instead of blocks, not indexable
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- splits input and then combines output, much higher disk usage
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### pxz
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- simpler code
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- uses OpenMP instead of pthreads
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- uses streams instead of blocks, not indexable
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- uses temporary files and does not combine them until the whole file is compressed, high disk and
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memory usage
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### pbzip2
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- not indexable
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- appears slow
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- bzip2 algorithm is non-ideal
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### pigz
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- not indexable
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### dictzip, idzip
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- not parallel
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