279 lines
8.1 KiB
Plaintext
279 lines
8.1 KiB
Plaintext
<!--
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doc/src/sgml/ref/ecpg-ref.sgml
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PostgreSQL documentation
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-->
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<refentry id="app-ecpg">
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<indexterm zone="app-ecpg">
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<primary>ecpg</primary>
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</indexterm>
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<refmeta>
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<refentrytitle><application>ecpg</application></refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo>Application</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname><application>ecpg</application></refname>
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<refpurpose>embedded SQL C preprocessor</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>ecpg</command>
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<arg choice="opt" rep="repeat"><replaceable>option</replaceable></arg>
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<arg choice="plain" rep="repeat"><replaceable>file</replaceable></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1 id="app-ecpg-description">
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<title>Description</title>
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<para>
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<command>ecpg</command> is the embedded SQL preprocessor for C
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programs. It converts C programs with embedded SQL statements to
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normal C code by replacing the SQL invocations with special
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function calls. The output files can then be processed with any C
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compiler tool chain.
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</para>
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<para>
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<command>ecpg</command> will convert each input file given on the
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command line to the corresponding C output file. If an input file
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name does not have any extension, <filename>.pgc</filename> is
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assumed. The file's extension will be replaced
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by <filename>.c</filename> to construct the output file name.
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But the output file name can be overridden using the
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<option>-o</option> option.
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</para>
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<para>
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If an input file name is just <literal>-</literal>,
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<command>ecpg</command> reads the program from standard input
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(and writes to standard output, unless that is overridden
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with <option>-o</option>).
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</para>
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<para>
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This reference page does not describe the embedded SQL language.
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See <xref linkend="ecpg"/> for more information on that topic.
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</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>
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<command>ecpg</command> accepts the following command-line
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arguments:
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<variablelist>
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<varlistentry>
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<term><option>-c</option></term>
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<listitem>
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<para>
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Automatically generate certain C code from SQL code. Currently, this
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works for <literal>EXEC SQL TYPE</literal>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-C <replaceable>mode</replaceable></option></term>
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<listitem>
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<para>
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Set a compatibility mode. <replaceable>mode</replaceable> can
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be <literal>INFORMIX</literal>,
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<literal>INFORMIX_SE</literal>, or <literal>ORACLE</literal>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-D <replaceable>symbol</replaceable></option></term>
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<listitem>
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<para>
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Define a C preprocessor symbol.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-h</option></term>
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<listitem>
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<para>
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Process header files. When this option is specified, the output file
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extension becomes <literal>.h</literal> not <literal>.c</literal>,
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and the default input file extension is <literal>.pgh</literal>
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not <literal>.pgc</literal>. Also, the <option>-c</option> option is
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forced on.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-i</option></term>
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<listitem>
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<para>
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Parse system include files as well.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-I <replaceable class="parameter">directory</replaceable></option></term>
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<listitem>
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<para>
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Specify an additional include path, used to find files included
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via <literal>EXEC SQL INCLUDE</literal>. Defaults are
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<filename>.</filename> (current directory),
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<filename>/usr/local/include</filename>, the
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<productname>PostgreSQL</productname> include directory which
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is defined at compile time (default:
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<filename>/usr/local/pgsql/include</filename>), and
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<filename>/usr/include</filename>, in that order.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-o <replaceable>filename</replaceable></option></term>
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<listitem>
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<para>
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Specifies that <command>ecpg</command> should write all
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its output to the given <replaceable>filename</replaceable>.
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Write <literal>-o -</literal> to send all output to standard output.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-r <replaceable>option</replaceable></option></term>
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<listitem>
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<para>
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Selects run-time behavior. <replaceable>Option</replaceable> can be
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one of the following:
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<variablelist>
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<varlistentry>
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<term><option>no_indicator</option></term>
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<listitem>
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<para>
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Do not use indicators but instead use special values to represent
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null values. Historically there have been databases using this approach.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>prepare</option></term>
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<listitem>
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<para>
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Prepare all statements before using them. Libecpg will keep a cache of
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prepared statements and reuse a statement if it gets executed again. If the
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cache runs full, libecpg will free the least used statement.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>questionmarks</option></term>
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<listitem>
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<para>
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Allow question mark as placeholder for compatibility reasons.
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This used to be the default long ago.
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</para>
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</listitem>
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</varlistentry>
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</variablelist></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-t</option></term>
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<listitem>
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<para>
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Turn on autocommit of transactions. In this mode, each SQL command is
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automatically committed unless it is inside an explicit
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transaction block. In the default mode, commands are committed
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only when <command>EXEC SQL COMMIT</command> is issued.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-v</option></term>
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<listitem>
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<para>
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Print additional information including the version and the
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"include" path.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--version</option></term>
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<listitem>
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<para>
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Print the <application>ecpg</application> version and exit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-?</option></term>
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<term><option>--help</option></term>
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<listitem>
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<para>
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Show help about <application>ecpg</application> command line
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arguments, and exit.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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When compiling the preprocessed C code files, the compiler needs to
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be able to find the <application>ECPG</application> header files in the
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<productname>PostgreSQL</productname> include directory. Therefore, you might
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have to use the <option>-I</option> option when invoking the compiler
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(e.g., <literal>-I/usr/local/pgsql/include</literal>).
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</para>
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<para>
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Programs using C code with embedded SQL have to be linked against
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the <filename>libecpg</filename> library, for example using the
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linker options <literal>-L/usr/local/pgsql/lib -lecpg</literal>.
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</para>
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<para>
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The value of either of these directories that is appropriate for
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the installation can be found out using <xref
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linkend="app-pgconfig"/>.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>
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If you have an embedded SQL C source file named
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<filename>prog1.pgc</filename>, you can create an executable
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program using the following sequence of commands:
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<programlisting>
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ecpg prog1.pgc
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cc -I/usr/local/pgsql/include -c prog1.c
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cc -o prog1 prog1.o -L/usr/local/pgsql/lib -lecpg
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</programlisting></para>
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</refsect1>
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</refentry>
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