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ECPG(1) 		  PostgreSQL 18.6 Documentation 		 ECPG(1)

NAME
     ecpg - embedded SQL C preprocessor

SYNOPSIS
     ecpg [option...] file...

DESCRIPTION
     ecpg  is  the  embedded SQL preprocessor for C programs. It converts C pro-
     grams 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  corre-
     sponding  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  Chap-
     ter 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  ORA-
	 CLE.

     -D symbol[=value]
	 Define  a  preprocessor symbol, equivalently to the EXEC SQL DEFINE di-
	 rective. 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/in-
	 clude, the PostgreSQL include directory which	is  defined  at  compile
	 time (default: /usr/local/pgsql/include), and /usr/include, in that or-
	 der.

     -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 ap-
	     proach.

	 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. There-
     fore, 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/lo-
     cal/pgsql/lib -lecpg.

     The value of either of these directories that is appropriate  for	the  in-
     stallation 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 18.6 		      2026				 ECPG(1)

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