Spawned Processes Do Not Always Handle Signals Properly

MS-DOS                      | WINDOWS

The information in this article applies to:

• The C Run-time (CRT), included with:

      - Microsoft C for MS-DOS, versions 5.1, 6.0, 6.0a, and 6.0ax
      - Microsoft C/C++ for MS-DOS, version 7.0
      - Microsoft Visual C++ for Windows, versions 1.0 and 1.5
  

In the following example, the CTRL+C signal is not handled as expected within the spawned process:

   /*Compile options needed: none
   */

   #include <stdio.h>
   #include <process.h>

   void main( void )
   {
       int err;

       err = system( "TYPE TEST.TXT | MORE" );

       printf( "Return from system: %d\n", err );
   }

This is a limitation of MS-DOS and the way child processes handle certain signals, not a problem with the C compiler. Interrupting an assembly language program that calls MS-DOS Interrupt 0x4B to spawn "COMMAND /c TYPE TEST.TXT | MORE" gives the same results.