Slax core module is 2% smaller than before (52MB versus 51MB), so the difference for full Slax will be somewhere between 5-10 megabytes less of data at the cost of adding "-Xbcj x86" parameter to mksquashfs command. Mksquashfs then tries to compress all blocks without any filter at first, and then it tries again for each given filter, and chooses the best compression.įor Slax, we simply add x86 filter since it will do the job for both 32bit and 64bit architectures. Using BCJ filters is mksquashfs is simple, just add -Xbcj xxx as a parameter after -comp xz, where xxx is a list of filters. xopen selects the most efficient method for reading or writing a compressed file. Supported compression formats are currently gzip, bzip2, xz and optionally Zstandard. ![]() More than 100 million people use GitHub to discover, fork, and contribute to over 330 million projects. dev/sda1), -verbose shows the current size read from input file (128 MiB below). To associate your repository with the xz topic, visit your repos landing page and select 'manage topics.' GitHub is where people build software. This normalization is of course machine dependent, thus the filter needs to be different for x86 code and also different for, say, sparc. This Python module provides an xopen function that works like the built-in open function but also transparently deals with compressed files. When I use xz to compress a block device (e.g. This means for example that some of the jumps may be converted from the machine language "jump 1655 bytes backwards" style notation to normalized "jump to address 5554" style notation all jumps to 5554, perhaps a common subroutine, are thus encoded identically, making them more compressible. The filter normalizes jump targets before compression by changing relative position into absolute values. What's that? Simply said it is a filter, which takes the compressed block and thinks about it as if it was an executable code (in most cases it is). For more information about everything we can do, you can go to the page man xz.XZ (LZMA) compression is the best available for our purposes, yet it can be even better, since LZMA supports BCJ filters. In this article, we only look at some examples for compressing and decompressing. This is a good tool for compressing files. Using -l we can see the information about a compressed file. Hence, we list the contents of an archive by passing the -t as follows and then unzip tar. Sometimes we don’t know file names in advance. tar -xf babys-3rd-cake-day.jpg sales.txt. We can test the integrity of the compressed files using the -t option. We extract a given file names from a file by using the following syntax: tar -xf resume.pdf. Tar -cJf *.txt Check the integrity of compressed files To achieve this same end, we can also use: The following is an example of the use to get a file with the extension tar.xz. Xz -k -qv android-x86_ Create a tar.xz file Compressing Files by Giving Filenames to Compressor Applications Usually, we provide filenames as arguments for compressor applications. We can also enable the verbose mode with -v, as it's shown in the following: xz -k -q android-x86_ ![]() If we are interested in executing the compression in silent mode, we will only have to add the -q option. In case of having a small amount of system memory and wanting to compress a huge file, we will have the possibility of using the -memory option = limit ( the limit value can be in MB or as a percentage of RAM) to set a memory usage limit for compression: xz -k -best -memlimit-compress=10% android-x86_ Enable silent mode Some examples of how to set these levels are the following: xz -k -8 android-x86_ We will also be able to use aliases as –fast ( it will be fast, but with less compression) to set as value 0 and –best to set as value 9 ( slow but higher compression). This tool supports different preset levels of compression ( 0 to 9. If an operation fails, for example if there is a compressed file with the same name, we will use the -f option to force the process: xz -kf android-x86_ Set compression levels We can also achieve the same with the option unxz: unxz android-x86_ Force compression To decompress a file, we will be able to use the -d option: xz -d android-x86_
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