apxs - APache eXtenSion tool
apxs - APache eXtenSion tool
apxs is a tool for building and installing extension modules for the Apache HyperText Transfer Protocol (HTTP) server. This is achieved by building a dynamic shared object (DSO) from one or more source or object
files which then can be loaded into the Apache server under runtime via the
LoadModule directive from
So to use this extension mechanism your platform has to support the DSO feature and your Apache
httpd binary has to be built with the
mod_so module. The
apxs tool automatically complains if this is not the case. You can check this yourself by manually running the command
$ httpd -l
mod_so should be part of the displayed list. If these requirements are fulfilled you can easily extend your Apache server's functionality by installing your own modules with the DSO mechanism by the help of this
$ apxs -i -a -c mod_foo.c gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c ld -Bshareable -o mod_foo.so mod_foo.o cp mod_foo.so /path/to/apache/modules/mod_foo.so chmod 755 /path/to/apache/modules/mod_foo.so [activating module `foo' in /path/to/apache/etc/httpd.conf] $ apachectl restart /path/to/apache/sbin/apachectl restart: httpd not running, trying to start [Tue Mar 31 11:27:55 1998] [debug] mod_so.c(303): loaded module foo_module /path/to/apache/sbin/apachectl restart: httpd started $ _
files can be any C source file (.c), a object file (.o) or even a library archive (.a). The
apxs tool automatically recognizes these extensions and automatically used the C source files for compilation while just using the object and archive files for the linking phase. But when using such pre-compiled objects make sure they are compiled for position independent code (PIC) to be able to use them for a dynamically loaded shared object. For instance with GCC you always just have to use
-fpic. For other C compilers consult its manual page or at watch for the flags
apxs uses to compile the object files.
For more details about DSO support in Apache read the documentation of
mod_so or perhaps even read the
src/modules/standard/mod_so.c source file.
apxs -g [ -S name=value ] -n modname
apxs -q [ -v ] [ -S name=value ] query ...
apxs -c [ -S name=value ] [ -o dsofile ] [ -I incdir ] [ -D name=value ] [ -L libdir ] [ -l libname ] [ -Wc,compiler-flags ] [ -Wl,linker-flags ] files ...
apxs -i [ -S name=value ] [ -n modname ] [ -a ] [ -A ] dso-file ...
apxs -e [ -S name=value ] [ -n modname ] [ -a ] [ -A ] dso-file ...
- This explicitly sets the module name for the
-g(template generation) option. Use this to explicitly specify the module name. For option
-gthis is required, for option
apxstool tries to determine the name from the source or (as a fallback) at least by guessing it from the filename.
Performs a query for variables and environment settings used to build
httpd. When invoked without
queryparameters, it prints all known variables and their values. The optional
-vparameter formats the list output. Use this to manually determine settings used to build the httpd that will load your module. For instance use
INC=-I`apxs -q INCLUDEDIR`
inside your own Makefiles if you need manual access to Apache's C header files.
- This option changes the apxs settings described above.
Template Generation Options
- This generates a subdirectory
-n) and there two files: A sample module source file named
mod_name.cwhich can be used as a template for creating your own modules or as a quick start for playing with the apxs mechanism. And a corresponding
Makefilefor even easier build and installing of this module.
DSO Compilation Options
- This indicates the compilation operation. It first compiles the C source files (.c) of
filesinto corresponding object files (.o) and then builds a dynamically shared object in
dsofileby linking these object files plus the remaining object files (.o and .a) of
files. If no
-ooption is specified the output file is guessed from the first filename in
filesand thus usually defaults to
- Explicitly specifies the filename of the created dynamically shared object. If not specified and the name cannot be guessed from the
fileslist, the fallback name
- This option is directly passed through to the compilation command(s). Use this to add your own defines to the build process.
- This option is directly passed through to the compilation command(s). Use this to add your own include directories to search to the build process.
- This option is directly passed through to the linker command. Use this to add your own library directories to search to the build process.
- This option is directly passed through to the linker command. Use this to add your own libraries to search to the build process.
- This option passes
compiler-flagsas additional flags to the
libtool --mode=compilecommand. Use this to add local compiler-specific options.
- This option passes
linker-flagsas additional flags to the
libtool --mode=linkcommand. Use this to add local linker-specific options.
- This option causes apxs to link against the apr/apr-util libraries. This is useful when compiling helper programs that use the apr/apr-util libraries.
DSO Installation and Configuration Options
- This indicates the installation operation and installs one or more dynamically shared objects into the server's
- This activates the module by automatically adding a corresponding
LoadModuleline to Apache's
httpd.confconfiguration file, or by enabling it if it already exists.
- Same as option
-abut the created
LoadModuledirective is prefixed with a hash sign (
#), i.e., the module is just prepared for later activation but initially disabled.
- This indicates the editing operation, which can be used with the
-Aoptions similarly to the
-ioperation to edit Apache's
httpd.confconfiguration file without attempting to install the module.
Assume you have an Apache module named
mod_foo.c available which should extend Apache's server functionality. To accomplish this you first have to compile the C source into a shared object suitable for loading into the Apache server under runtime via the following command:
$ apxs -c mod_foo.c /path/to/libtool --mode=compile gcc ... -c mod_foo.c /path/to/libtool --mode=link gcc ... -o mod_foo.la mod_foo.slo $ _
Then you have to update the Apache configuration by making sure a
LoadModule directive is present to load this shared object. To simplify this step
apxs provides an automatic way to install the shared object in its "modules" directory and updating the
httpd.conf file accordingly. This can be achieved by running:
$ apxs -i -a mod_foo.la /path/to/instdso.sh mod_foo.la /path/to/apache/modules /path/to/libtool --mode=install cp mod_foo.la /path/to/apache/modules ... chmod 755 /path/to/apache/modules/mod_foo.so [activating module `foo' in /path/to/apache/conf/httpd.conf] $ _
This way a line named
LoadModule foo_module modules/mod_foo.so
is added to the configuration file if still not present. If you want to have this disabled per default use the
-A option, i.e.
$ apxs -i -A mod_foo.c
For a quick test of the apxs mechanism you can create a sample Apache module template plus a corresponding Makefile via:
$ apxs -g -n foo Creating [DIR] foo Creating [FILE] foo/Makefile Creating [FILE] foo/modules.mk Creating [FILE] foo/mod_foo.c Creating [FILE] foo/.deps $ _
Then you can immediately compile this sample module into a shared object and load it into the Apache server:
$ cd foo $ make all reload apxs -c mod_foo.c /path/to/libtool --mode=compile gcc ... -c mod_foo.c /path/to/libtool --mode=link gcc ... -o mod_foo.la mod_foo.slo apxs -i -a -n "foo" mod_foo.la /path/to/instdso.sh mod_foo.la /path/to/apache/modules /path/to/libtool --mode=install cp mod_foo.la /path/to/apache/modules ... chmod 755 /path/to/apache/modules/mod_foo.so [activating module `foo' in /path/to/apache/conf/httpd.conf] apachectl restart /path/to/apache/sbin/apachectl restart: httpd not running, trying to start [Tue Mar 31 11:27:55 1998] [debug] mod_so.c(303): loaded module foo_module /path/to/apache/sbin/apachectl restart: httpd started $ _
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