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AX_CHECK_ZLIB([action-if-found], [action-if-not-found])


This macro searches for an installed zlib library. If nothing was specified when calling configure, it searches first in /usr/local and then in /usr, /opt/local and /sw. If the –with-zlib=DIR is specified, it will try to find it in DIR/include/zlib.h and DIR/lib/libz.a. If –without-zlib is specified, the library is not searched at all.

If either the header file (zlib.h) or the library (libz) is not found, shell commands ’action-if-not-found’ is run. If ’action-if-not-found’ is not specified, the configuration exits on error, asking for a valid zlib installation directory or –without-zlib.

If both header file and library are found, shell commands ’action-if-found’ is run. If ’action-if-found’ is not specified, the default action appends ’-I${ZLIB_HOME}/include’ to CPFLAGS, appends ’-L$ZLIB_HOME}/lib’ to LDFLAGS, prepends ’-lz’ to LIBS, and calls AC_DEFINE(HAVE_LIBZ). You should use autoheader to include a definition for this symbol in a config.h file. Sample usage in a C/C++ source is as follows:

  #ifdef HAVE_LIBZ
  #include <zlib.h>
  #endif /* HAVE_LIBZ */

Source Code

Download the latest version of ax_check_zlib.m4 or browse the macro’s revision history.


Copyright © 2008 Loic Dachary
Copyright © 2010 Bastien Chevreux

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <>.

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