apxs(8apache2)
NAME
apxs - APache eXtenSion tool
SYNOPSIS
apxs -g [ -S variable=value ] -n name
apxs -q [ -S variable=value ] query ...
apxs -c [ -S variable=value ] [ -o dsofile ] [ -I incdir ] [ -D vari-
able[=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 ...
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 run-
time 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 automatically uses the C source files for compila-
tion while 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 Independend Code (PIC) to be able to use them for
a DSO. For instance with GCC you always just have to use -fpic. For
other C compilers please consult its manual page 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 documen-
tation of mod_so.
OPTIONS
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 set-
tings. The query parameters can be one or more of the fol-
lowing 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
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 eas-
ier 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 usu-
ally 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 com-
mand. 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 com-
mand. 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-spe-
cific 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 corre-
sponding LoadModule line to Apache's httpd.conf configura-
tion 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 pre-
pared 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 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 Load-
Module 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
to have 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 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 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 recognized 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.
SEE ALSO
apachectl(1), httpd(8).
February 2004 apxs(8)
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