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.TH ZLIB 3 "17 Feb 2026" |
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.SH NAME |
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zlib \- compression/decompression library |
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.SH SYNOPSIS |
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[see |
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.I zlib.h |
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for full description] |
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.SH DESCRIPTION |
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The |
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.I zlib |
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library is a general purpose data compression library. |
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The code is thread safe, assuming that the standard library functions |
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used are thread safe, such as memory allocation routines. |
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It provides in-memory compression and decompression functions, |
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including integrity checks of the uncompressed data. |
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This version of the library supports only one compression method (deflation) |
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but other algorithms may be added later |
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with the same stream interface. |
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.LP |
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Compression can be done in a single step if the buffers are large enough |
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or can be done by repeated calls of the compression function. |
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In the latter case, |
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the application must provide more input and/or consume the output |
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(providing more output space) before each call. |
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.LP |
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The library also supports reading and writing files in |
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.IR gzip (1) |
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(.gz) format |
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with an interface similar to that of stdio. |
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.LP |
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The library does not install any signal handler. |
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The decoder checks the consistency of the compressed data, |
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so the library should never crash even in the case of corrupted input. |
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.LP |
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All functions of the compression library are documented in the file |
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.IR zlib.h . |
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The distribution source includes examples of use of the library |
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in the files |
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.I test/example.c |
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and |
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.IR test/minigzip.c, |
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as well as other examples in the |
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.IR examples/ |
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directory. |
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.LP |
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Changes to this version are documented in the file |
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.I ChangeLog |
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that accompanies the source. |
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.LP |
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.I zlib |
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is built in to many languages and operating systems, including but not limited to |
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Java, Python, .NET, PHP, Perl, Ruby, Swift, and Go. |
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.LP |
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An experimental package to read and write files in the .zip format, |
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written on top of |
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.I zlib |
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by Gilles Vollant ([email protected]), |
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is available at: |
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.IP |
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https://www.winimage.com/zLibDll/minizip.html |
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and also in the |
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.I contrib/minizip |
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directory of the main |
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.I zlib |
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source distribution. |
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.SH "SEE ALSO" |
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The |
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.I zlib |
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web site can be found at: |
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.IP |
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https://zlib.net/ |
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.LP |
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The data format used by the |
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.I zlib |
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library is described by RFC |
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(Request for Comments) 1950 to 1952 at: |
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.IP |
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https://datatracker.ietf.org/doc/html/rfc1950 (for the zlib header and trailer format) |
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.br |
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https://datatracker.ietf.org/doc/html/rfc1951 (for the deflate compressed data format) |
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.br |
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https://datatracker.ietf.org/doc/html/rfc1952 (for the gzip header and trailer format) |
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.LP |
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Mark Nelson wrote an article about |
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.I zlib |
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for the Jan. 1997 issue of Dr. Dobb's Journal; |
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a copy of the article is available at: |
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.IP |
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https://zlib.net/nelson/ |
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.SH "REPORTING PROBLEMS" |
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Before reporting a problem, |
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please check the |
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.I zlib |
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web site to verify that you have the latest version of |
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.IR zlib ; |
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otherwise, |
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obtain the latest version and see if the problem still exists. |
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Please read the |
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.I zlib |
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FAQ at: |
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.IP |
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https://zlib.net/zlib_faq.html |
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.LP |
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before asking for help. |
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Send questions and/or comments to [email protected], |
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or (for the Windows DLL version) to Gilles Vollant ([email protected]). |
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.SH AUTHORS AND LICENSE |
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Version 1.3.2 |
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.LP |
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Copyright (C) 1995-2026 Jean-loup Gailly and Mark Adler |
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.LP |
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This software is provided 'as-is', without any express or implied |
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warranty. In no event will the authors be held liable for any damages |
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arising from the use of this software. |
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.LP |
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Permission is granted to anyone to use this software for any purpose, |
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including commercial applications, and to alter it and redistribute it |
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freely, subject to the following restrictions: |
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.LP |
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.nr step 1 1 |
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.IP \n[step]. 3 |
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The origin of this software must not be misrepresented; you must not |
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claim that you wrote the original software. If you use this software |
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in a product, an acknowledgment in the product documentation would be |
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appreciated but is not required. |
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.IP \n+[step]. |
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Altered source versions must be plainly marked as such, and must not be |
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misrepresented as being the original software. |
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.IP \n+[step]. |
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This notice may not be removed or altered from any source distribution. |
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.LP |
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Jean-loup Gailly Mark Adler |
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.br |
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[email protected] [email protected] |
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.LP |
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The deflate format used by |
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.I zlib |
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was defined by Phil Katz. |
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The deflate and |
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.I zlib |
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specifications were written by L. Peter Deutsch. |
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Thanks to all the people who reported problems and suggested various |
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improvements in |
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.IR zlib ; |
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who are too numerous to cite here. |
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.LP |
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UNIX manual page by R. P. C. Rodgers, |
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U.S. National Library of Medicine ([email protected]). |
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.\" end of man page |
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