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
$ _