path: root/usr.sbin/httpd/src/support/apxs.8

.TH apxs 8 "April 1998"
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.SH NAME
apxs \- APache eXtenSion tool
.SH SYNOPSIS
.B apxs
.B \-g
.BI \-n " modname"

.B apxs
.B \-q
.IR query " ..."

.B apxs
.B \-c
[
.BI \-o " dsofile"
]
[
.BI \-I " incdir"
]
[
.BI \-D " name=value"
]
[
.BI \-L " libdir"
]
[
.BI \-l " libname"
]
.IR files " ..."

.B apxs
.B \-i
[
.BI \-n " modname"
]
[
.B \-a
]
[
.B \-A
]
.IR dsofile " ..."
.PP
.SH DESCRIPTION
.B 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
.I files
which then can be loaded into
the Apache server under runtime via the
.B LoadModule
directive from
.BR mod_so.

So to use this extension mechanism your platform has
to support the DSO feature and your
Apache
.B httpd
binary has to be built with the
.B mod_so
module.
The
.B apxs
tool automatically complains if this is not the case.
You can check this yourself by manually running the command

.nf
  $ httpd -l
.fi

The module
.B 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
.B apxs
tool:

.nf
  $ 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
  $ _
.fi

The arguments
.I files
can be any C source file (.c), a object file (.o) or
even a library archive (.a). The
.B 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
.BR -fpic .
For other
C compilers consult its manual
page or at watch for the flags
.B apxs
uses to compile the object files.

For more details about DSO support in Apache read the documentation
of
.B mod_so
or perhaps even read the
.B src/modules/standard/mod_so.c
source file.

.PP
.SH OPTIONS
Common options:
.TP 12
.BI \-n " modname"
This explicitly sets the module name for the
.B \-i
(install)
and
.B \-g
(template generation) option. Use this to explicitly specify the module name.
For option
.B \-g
this is required, for option
.B \-i
the
.B apxs
tool tries to determine the name from the source or (as a fallback) at least
by guessing it from the filename.
.PP
Query options:
.TP 12
.B \-q 
Performs a query for 
.BR apxs 's
knowledge about certain settings. The
.I query
parameters can be one or more of the following strings:
.nf
  CC             PREFIX     
  LD             SBINDIR    
  CFLAGS         INCLUDEDIR     
  CFLAGS_SHLIB   LIBEXECDIR 
  LDFLAGS_SHLIB  SYSCONFDIR 
.fi
Use this for manually determining settings. For instance use
.nf
  INC=-I`apxs -q INCLUDEDIR`
.fi
inside your own Makefiles if you need manual access
to Apache's C header files.
.PP
Template Generation options:
.TP 12
.B \-g
This generates a subdirectory
.I name
(see option
.BR \-n ")"
and there two files: A sample module source file named
.BI 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
.B Makefile
for even easier build and installing of this module.
.PP
DSO compilation options:
.TP 12
.B \-c
This indicates the compilation operation. It first compiles the C source
files (.c) of
.I files
into corresponding object files (.o) and then builds a dynamically shared object in
.I dsofile
by linking these object files plus the remaining
object files (.o and .a) of
.I files
If no
.B \-o
option is specified
the output file is guessed from the first filename in
.I files
and thus usually defaults to
.BI mod_ name.so
.TP 12
.BI \-o " dsofile"
Explicitly specifies the filename of the created dynamically shared object. If
not specified and the name cannot be guessed from the
.I files
list, the fallback name
.B mod_unknown.so
is used.
.TP 12
.BI \-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.
.TP 12
.BI \-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.
.TP 12
.BI \-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.
.TP 12
.BI \-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.
.PP
DSO installation options:
.TP 12
.B \-i
This indicates the installation operartion and installs one or more
dynamically shared objects into the
servers
.I libexec
directory.
.TP 12
.B \-a
This additionally activates the module 
by automatically adding a corresponding
.B LoadModule
line to Apache's
.B httpd.conf
configuration file (only if still no such entry exists).
.TP 12
.B \-A
Same as option
.B \-a
but the created 
.B LoadModule
directive is
prefixed with a hash sign (#), i.e. the module is
just prepared for later activation but initially disabled. 
.PD
.SH 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:

.nf
  $ 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
  $ _
.fi

Then you have to update the Apache configuration by making sure a
.B LoadModule
directive is present to load this shared object. To simplify this
step
.B apxs
provides an automatic way to install the shared object in its
"libexec" directory and updating the
.B httpd.conf
file accordingly. This can be achieved by running:

.nf
  $ 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]
  $ _
.fi

This way a line named

.nf
  LoadModule foo_module libexec/mod_foo.so
.fi

is added to the configuration file if still not present.
If you want to have this this disabled per default use the
.B \-A
option, i.e.

.nf
  $ apxs -i -A mod_foo.c
.fi

For a quick test of the APXS mechanism you can create a sample Apache module
template plus a corresponding Makefile via:

.nf
  $ apxs -g -n foo
  Creating [DIR]  foo
  Creating [FILE] foo/Makefile
  Creating [FILE] foo/mod_foo.c
  $ _
.fi

Then you can immediately compile this sample module into a shared object and
load it into the Apache server:

.nf
  $ 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
  $ _
.fi

You can even use
.B apxs
to compile complex modules outside the Apache source tree, like PHP3:

.nf
  $ 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
  $ _
.fi

because
.B 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.

.PD
.SH SEE ALSO
.BR apachectl(1),
.BR httpd(8).
.