NAME

       ecpg - embedded SQL C preprocessor

SYNOPSIS

       ecpg [option...] file...

DESCRIPTION

       ecpg 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.

       ecpg will convert each input file given on the command line to the corresponding C output file. If an
       input file name does not have any extension, .pgc is assumed. The file's extension will be replaced by .c
       to construct the output file name. But the output file name can be overridden using the -o option.

       If an input file name is just -, ecpg reads the program from standard input (and writes to standard
       output, unless that is overridden with -o).

       This reference page does not describe the embedded SQL language. See Chapter 34 for more information on
       that topic.

OPTIONS

       ecpg accepts the following command-line arguments:

       -c
           Automatically generate certain C code from SQL code. Currently, this works for EXEC SQL TYPE.

       -C mode
           Set a compatibility mode.  mode can be INFORMIX, INFORMIX_SE, or ORACLE.

       -D symbol[=value]
           Define a preprocessor symbol, equivalently to the EXEC SQL DEFINE directive. If no value is
           specified, the symbol is defined with the value 1.

       -h
           Process header files. When this option is specified, the output file extension becomes .h not .c, and
           the default input file extension is .pgh not .pgc. Also, the -c option is forced on.

       -i
           Parse system include files as well.

       -I directory
           Specify an additional include path, used to find files included via EXEC SQL INCLUDE. Defaults are .
           (current directory), /usr/local/include, the PostgreSQL include directory which is defined at compile
           time (default: /usr/local/pgsql/include), and /usr/include, in that order.

       -o filename
           Specifies that ecpg should write all its output to the given filename. Write -o - to send all output
           to standard output.

       -r option
           Selects run-time behavior.  Option can be one of the following:

           no_indicator
               Do not use indicators but instead use special values to represent null values. Historically there
               have been databases using this approach.

           prepare
               Prepare all statements before using them. Libecpg will keep a cache of prepared statements and
               reuse a statement if it gets executed again. If the cache runs full, libecpg will free the least
               used statement.

           questionmarks
               Allow question mark as placeholder for compatibility reasons. This used to be the default long
               ago.

       -t
           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
           EXEC SQL COMMIT is issued.

       -v
           Print additional information including the version and the "include" path.

       --version
           Print the ecpg version and exit.

       -?
       --help
           Show help about ecpg command line arguments, and exit.

NOTES

       When compiling the preprocessed C code files, the compiler needs to be able to find the ECPG header files
       in the PostgreSQL include directory. Therefore, you might have to use the -I option when invoking the
       compiler (e.g., -I/usr/local/pgsql/include).

       Programs using C code with embedded SQL have to be linked against the libecpg library, for example using
       the linker options -L/usr/local/pgsql/lib -lecpg.

       The value of either of these directories that is appropriate for the installation can be found out using
       pg_config(1).

EXAMPLES

       If you have an embedded SQL C source file named prog1.pgc, you can create an executable program using the
       following sequence of commands:

           ecpg prog1.pgc
           cc -I/usr/local/pgsql/include -c prog1.c
           cc -o prog1 prog1.o -L/usr/local/pgsql/lib -lecpg

PostgreSQL 17.5                                       2025                                               ECPG(1)