APXS(1) apxs APXS(1)
NAME
apxs - APache eXtenSion tool
SYNOPSIS
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 ...
SUMMARY
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 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 mechanism 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 variables and environment settings used to
build httpd. When invoked without query parameters, it prints
all known variables and their values. The optional -v parameter
formats the list output. .PP Use this to manually determine
settings used to build the httpd that will load your module. For
instance use INC=-I`apxs -q INCLUDEDIR` .PP inside your own
Makefiles 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 usually
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.
-p 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
-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 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
$ _
Apache HTTP Server 2018-07-06 APXS(1)
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