how to execute a C program via trigger ?

Hi,    I am using Red Hat 6.1 + PostgreSQL 7.0.3. All of
my
applications are developed by C and ECPG.  I would
like to know how to execute a C program by Trigger,for
example:

  1. I have a program my_c_program.c shuch as:

#include <stdio.h>
main()
{  printf("Hello World !\n");
}
  2. I create a table foo by following command

CREATE TABLE foo(x      int4);
  3. create a trigger  foo_trig :

create trigger foo_trig after update   on foo for each row execute procedure sql_c();    4. I don't know how to design
sql_c(),can anyone     give a small plpsql program that can execute     my_c_program?  
 
  regards,    S.F. Lee


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