APXS(8) apxs APXS(8)
NAME
apxs - APache eXtenSion tool
SYNOPSIS
apxs -g [ -S name=value ] -n modname
apxs -q [ -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 ...
SUMMARY
apxs is a tool for building and installing extension modules for the Apache HyperText Transfer Proto-col Protocol
col (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 mod_so.
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
The module 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 mecha-nism mechanism
nism by the help of this apxs tool:
$ 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
$ _
The arguments 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.
OPTIONS
Common Options
-n modname
This explicitly sets the module name for the -i (install) and -g (template generation) option.
Use this to explicitly specify the module name. For option -g this is required, for option -i
the apxs tool tries to determine the name from the source or (as a fallback) at least by
guessing it from the filename.
Query Options
-q Performs a query for apxs's knowledge about certain settings. The query parameters can be one
or more of the following strings: CC, CFLAGS, CFLAGS_SHLIB, INCLUDEDIR, LD_SHLIB,
LDFLAGS_SHLIB, LIBEXECDIR, LIBS_SHLIB, SBINDIR, SYSCONFDIR, TARGET. .PP Use this for manually
determining settings. For instance use INC=-I`apxs -q INCLUDEDIR` .PP inside your own Make-files Makefiles
files if you need manual access to Apache's C header files.
Configuration Options
-S name=value
This option changes the apxs settings described above.
Template Generation Options
-g This generates a subdirectory name (see option -n) and there two files: A sample module source
file named mod_name.c which 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 Makefile for even easier
build and installing of this module.
DSO Compilation Options
-c This indicates the compilation operation. It first compiles the C source files (.c) of files
into corresponding object files (.o) and then builds a dynamically shared object in dsofile by
linking these object files plus the remaining object files (.o and .a) of files. If no -o
option is specified the output file is guessed from the first filename in files and thus usu-ally usually
ally defaults to mod_name.so.
-o dsofile
Explicitly specifies the filename of the created dynamically shared object. If not specified
and the name cannot be guessed from the files list, the fallback name mod_unknown.so is used.
-D name=value
This option is directly passed through to the compilation command(s). Use this to add your own
defines to the build process.
-I incdir
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.
-L libdir
This option is directly passed through to the linker command. Use this to add your own library
directories to search to the build process.
-l libname
This option is directly passed through to the linker command. Use this to add your own
libraries to search to the build process.
-Wc,compiler-flags
This option passes compiler-flags as additional flags to the libtool --mode=compile command.
Use this to add local compiler-specific options.
-Wl,linker-flags
This option passes linker-flags as additional flags to the libtool --mode=link command. Use
this to add local linker-specific options.
DSO Installation and Configuration Options
-i This indicates the installation operation and installs one or more dynamically shared objects
into the server's modules directory.
-a This activates the module by automatically adding a corresponding LoadModule line to Apache's
httpd.conf configuration file, or by enabling it if it already exists.
-A Same as option -a but the created LoadModule directive is prefixed with a hash sign (#), i.e.,
the module is just prepared for later activation but initially disabled.
-e This indicates the editing operation, which can be used with the -a and -A options similarly
to the -i operation to edit Apache's httpd.conf configuration file without attempting to
install the module.
EXAMPLES
Assume you have an Apache module named mod_foo.c available which should extend Apache's server func-tionality. functionality.
tionality. 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 corre-sponding corresponding
sponding 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
$ _
Apache HTTP Server 2004-10-01 APXS(8)
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