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<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/ecpg-ref.sgml,v 1.33 2010/02/19 03:50:03 momjian Exp $
PostgreSQL documentation
-->
<refentry id="APP-ECPG">
<refmeta>
<refentrytitle><application>ecpg</application></refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo>Application</refmiscinfo>
</refmeta>
<refnamediv>
<refname><application>ecpg</application></refname>
<refpurpose>embedded SQL C preprocessor</refpurpose>
</refnamediv>
<indexterm zone="app-ecpg">
<primary>ecpg</primary>
</indexterm>
<refsynopsisdiv>
<cmdsynopsis>
<command>ecpg</command>
<arg choice="opt" rep="repeat"><replaceable>option</replaceable></arg>
<arg choice="plain" rep="repeat"><replaceable>file</replaceable></arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id="APP-ECPG-description">
<title>Description</title>
<para>
<command>ecpg</command> is the embedded SQL preprocessor for C
programs. It converts C programs with embedded SQL statements to
normal C code by replacing the SQL invocations with special
function calls. The output files can then be processed with any C
compiler tool chain.
</para>
<para>
<command>ecpg</command> will convert each input file given on the
command line to the corresponding C output file. Input files
preferably have the extension <filename>.pgc</filename>, in which
case the extension will be replaced by <filename>.c</filename> to
determine the output file name. If the extension of the input file
is not <filename>.pgc</filename>, then the output file name is
computed by appending <literal>.c</literal> to the full file name.
The output file name can also be overridden using the
<option>-o</option> option.
</para>
<para>
This reference page does not describe the embedded SQL language.
See <xref linkend="ecpg"> for more information on that topic.
</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>
<command>ecpg</command> accepts the following command-line
arguments:
<variablelist>
<varlistentry>
<term><option>-c</option></term>
<listitem>
<para>
Automatically generate certain C code from SQL code. Currently, this
works for <literal>EXEC SQL TYPE</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-C <replaceable>mode</replaceable></option></term>
<listitem>
<para>
Set a compatibility mode. <replaceable>mode</replaceable> can
be <literal>INFORMIX</literal> or
<literal>INFORMIX_SE</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-D <replaceable>symbol</replaceable></option></term>
<listitem>
<para>
Define a C preprocessor symbol.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-i</option></term>
<listitem>
<para>
Parse system include files as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-I <replaceable class="parameter">directory</replaceable></option></term>
<listitem>
<para>
Specify an additional include path, used to find files included
via <literal>EXEC SQL INCLUDE</literal>. Defaults are
<filename>.</filename> (current directory),
<filename>/usr/local/include</filename>, the
<productname>PostgreSQL</productname> include directory which
is defined at compile time (default:
<filename>/usr/local/pgsql/include</filename>), and
<filename>/usr/include</filename>, in that order.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-o <replaceable>filename</replaceable></option></term>
<listitem>
<para>
Specifies that <command>ecpg</command> should write all
its output to the given <replaceable>filename</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-r <replaceable>option</replaceable></option></term>
<listitem>
<para>
Selects a run-time behavior. Currently,
<replaceable>option</replaceable> can only be
<literal>no_indicator</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</option></term>
<listitem>
<para>
Turn on autocommit of transactions. In this mode, each SQL command is
automatically committed unless it is inside an explicit
transaction block. In the default mode, commands are committed
only when <command>EXEC SQL COMMIT</command> is issued.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<listitem>
<para>
Print additional information including the version and the
include path.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--help</option></term>
<listitem>
<para>
Show a brief summary of the command usage, then exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--version</option></term>
<listitem>
<para>
Output version information, then exit.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
When compiling the preprocessed C code files, the compiler needs to
be able to find the <application>ECPG</> header files in the
<productname>PostgreSQL</> include directory. Therefore, you might
have to use the <option>-I</> option when invoking the compiler
(e.g., <literal>-I/usr/local/pgsql/include</literal>).
</para>
<para>
Programs using C code with embedded SQL have to be linked against
the <filename>libecpg</filename> library, for example using the
linker options <literal>-L/usr/local/pgsql/lib -lecpg</literal>.
</para>
<para>
The value of either of these directories that is appropriate for
the installation can be found out using <xref
linkend="app-pgconfig">.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
If you have an embedded SQL C source file named
<filename>prog1.pgc</filename>, you can create an executable
program using the following sequence of commands:
<programlisting>
ecpg prog1.pgc
cc -I/usr/local/pgsql/include -c prog1.c
cc -o prog1 prog1.o -L/usr/local/pgsql/lib -lecpg
</programlisting>
</para>
</refsect1>
</refentry>
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