apxs - APache eXtenSion tool
apxs -g [ -S variable=value ] -n name
apxs -q [ -S variable=value ] query ...
apxs -c [ -S variable=value ] [ -o dsofile ] [ -I incdir ]
[ -D variable[=value] ] [ -L libdir ] [ -l libname ] [
-Wc,compiler-flags ] [ -Wl,linker-flags ] files ...
apxs -i [ -S variable=value ] [ -n name ] [ -a ] [ -A ]
dsofile ...
apxs -e [ -S variable=value ] [ -n name ] [ -a ] [ -A ]
dsofile ...
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
can then be loaded into the Apache server at 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, with 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 argument files can be any C source file (.c), an
object file (.o) or even a library archive (.a). The apxs
tool automatically recognizes these extensions and automatically
uses the C source files for compilation, whereas
it just uses 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 DSO. For instance, with GCC you
just have to always use -fpic. For other C compilers,
please consult their manual pages or watch for the flags
apxs uses to compile the object files.
For more details about DSO support in Apache, first read
the background information about DSO in htdocs/manual/dso.html,
then read the documentation of mod_so.
Common options:
-n name 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 variable names:
CC TARGET
CFLAGS SBINDIR
CFLAGS_SHLIB INCLUDEDIR
LD_SHLIB LIBEXECDIR
LDFLAGS_SHLIB SYSCONFDIR
LIBS_SHLIB PREFIX
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 variable=value
This option changes the apxs settings
described above.
Template Generation options:
-g This generates a subdirectory name (see option
-n) and 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 building 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 DSO 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
DSO file. If not specified and the name
cannot be guessed from the files list, the
fallback name mod_unknown.so is used.
-D variable[=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 DSOs 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.
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 DSO 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 DSO.
To simplify this step apxs provides an automatic way to
install the DSO in the "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 this operation to be disabled, 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 Make-
file 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
DSO 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, because apxs automatically
recognizes C source files and object files.
$ 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
$ _
Only C source files are compiled, while remaining object
files are used for the linking phase.
apachectl(1), httpd(8).
April 1998 5 [ Back ] |
