apxs (8)
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
]
dsofile ...
apxs
-e
[
-S name=value
]
[
-n modname
]
[
-a
]
[
-A
]
dsofile ...
DESCRIPTION
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/libexec/mod_foo.so
chmod 755 /path/to/apache/libexec/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 automtaically 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 independend 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 TARGET
CFLAGS SBINDIR
CFLAGS_SHLIB INCLUDEDIR
LD_SHLIB LIBEXECDIR
LDFLAGS_SHLIB SYSCONFDIR
LIBS_SHLIB
Use this for manually determining settings. For instance use
INC=-I`apxs -q INCLUDEDIR`
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 compiler command.
Use this to add local compiler-specific options.
-Wl, linker-flags
This option passes
linker-flags
as additional flags to the linker 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
libexec
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
gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c
ld -Bshareable -o mod_foo.so mod_foo.o
$ _
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
"libexec" directory and updating the
httpd.conf
file accordingly. This can be achieved by running:
$ apxs -i -a mod_foo.c
cp mod_foo.so /path/to/apache/libexec/mod_foo.so
chmod 755 /path/to/apache/libexec/mod_foo.so
[activating module `foo' in /path/to/apache/etc/httpd.conf]
$ _
This way a line named
LoadModule foo_module libexec/mod_foo.so
is added to the configuration file if still not present.
If you want to have this 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/mod_foo.c
$ _
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
gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c
ld -Bshareable -o mod_foo.so mod_foo.o
apxs -i -a -n "foo" mod_foo.so
cp mod_foo.so /path/to/apache/libexec/mod_foo.so
chmod 755 /path/to/apache/libexec/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
$ _
You can even use
apxs
to compile complex modules outside the Apache source tree, like PHP3:
$ cd php3
$ ./configure --with-shared-apache=../apache-1.3
$ apxs -c -o libphp3.so mod_php3.c libmodphp3-so.a
gcc -fpic -DSHARED_MODULE -I/tmp/apache/include -c mod_php3.c
ld -Bshareable -o libphp3.so mod_php3.o libmodphp3-so.a
$ _
because
apxs
automatically recognized C source files and object files. Only C source files
are compiled while remaining object files are used for the linking phase.
SEE ALSO
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