apxs - APache eXtenSion tool
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 ...
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.
-
-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.
- -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.
-
-S name=value
- This option changes the apxs settings described above.
- -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.
- -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.
- -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.
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
$ _