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diff --git a/doc/lzma-intro.txt b/doc/lzma-intro.txt deleted file mode 100644 index bde8a059..00000000 --- a/doc/lzma-intro.txt +++ /dev/null @@ -1,107 +0,0 @@ - -Introduction to the lzma command line tool ------------------------------------------- - -Overview - - The lzma command line tool is similar to gzip and bzip2, but for - compressing and uncompressing .lzma files. - - -Supported file formats - - By default, the tool creates files in the new .lzma format. This can - be overriden with --format=FMT command line option. Use --format=alone - to create files in the old LZMA_Alone format. - - By default, the tool uncompresses both the new .lzma format and - LZMA_Alone format. This is to make it transparent to switch from - the old LZMA_Alone format to the new .lzma format. Since both - formats use the same filename suffix, average user should never - notice which format was used. - - -Differences to gzip and bzip2 - - Standard input and output - - Both gzip and bzip2 refuse to write compressed data to a terminal and - read compressed data from a terminal. With gzip (but not with bzip2), - this can be overriden with the `--force' option. lzma follows the - behavior of gzip here. - - Usage of LZMA_OPT environment variable - - gzip and bzip2 read GZIP and BZIP2 environment variables at startup. - These variables may contain extra command line options. - - gzip and bzip2 allow passing not only options, but also end-of-options - indicator (`--') and filenames via the environment variable. No quoting - is supported with the filenames. - - Here are examples with gzip. bzip2 behaves identically. - - bash$ echo asdf > 'foo bar' - bash$ GZIP='"foo bar"' gzip - gzip: "foo: No such file or directory - gzip: bar": No such file or directory - - bash$ GZIP=-- gzip --help - gzip: --help: No such file or directory - - lzma silently ignores all non-option arguments given via the - environment variable LZMA_OPT. Like on the command line, everything - after `--' is taken as non-options, and thus ignored in LZMA_OPT. - - bash$ LZMA_OPT='--help' lzma --version # Displays help - bash$ LZMA_OPT='-- --help' lzma --version # Displays version - - -Filter chain presets - - Like in gzip and bzip2, lzma supports numbered presets from 1 to 9 - where 1 is the fastest and 9 the best compression. 1 and 2 are for - fast compressing with small memory usage, 3 to 6 for good compression - ratio with medium memory usage, and 7 to 9 for excellent compression - ratio with higher memory requirements. The default is 7 if memory - usage limit allows. - - In future, there will probably be an option like --preset=NAME, which - will contain more special presets for specific file types. - - It's also possible that there will be some heuristics to select good - filters. For example, the tool could detect when a .tar archive is - being compressed, and enable x86 filter only for those files in the - .tar archive that are ELF or PE executables for x86. - - -Specifying custom filter chains - - Custom filter chains are specified by using long options with the name - of the filters in correct order. For example, to pass the input data to - the x86 filter and the output of that to the LZMA filter, the following - command will do: - - lzma --x86 --lzma filename - - Some filters accept options, which are specified as a comma-separated - list of key=value pairs: - - lzma --delta=distance=4 --lzma=dict=4Mi,lc=8,lp=2 filename - - -Memory usage control - - By default, the command line tool limits memory usage to 1/3 of the - available physical RAM. If no preset or custom filter chain has been - given, the default preset will be used. If the memory limit is too - low for the default preset, the tool will silently switch to lower - preset. - - When a preset or a custom filter chain has been specified and the - memory limit is too low, an error message is displayed and no files - are processed. - - If the decoder hits the memory usage limit, an error is displayed and - no more files are processed. - |