Hi Thomas,

 TZ> I have to start a process with DosStartSesstion. This process
 TZ> communicates with the child process via an unnamed pipe. The pipe is
 TZ> used to redirect the stdin and stdout of the child process. Does
 TZ> anybody has a codefragment witch manage such a redirection. 

Unnamed pipes can transfer information between related processes only!
You may have to use DosExecPgm instead, but this wont work for
different types of programs (PM, Text mode, ...).

The following code fragment is derived from the sources of Eberhard
Mattes PM EMACS (pmterm.c):

    int inbound[2], outbound[2];

    if (pipe(inbound) < 0)
        crtError("Cannot open pipe for Server.");
    dup2(inbound[1], STDOUT_FILENO);     /* Replace stdout with pipe */
    close(inbound[1]);
    fcntl(inbound[0], F_SETFD, 1);

    if (pipe(outbound) < 0)
        crtError("Cannot open pipe for Server.");
    dup2(outbound[0], STDIN_FILENO);     /* Replace stdin with pipe */
    close(outbound[0]);
    fcntl(outbound[1], F_SETFD, 1);

inbound[0] is used to read from, outbound[1] to write to the program.

If you prefer the API calls, replace pipe, dup2, close with
DosCreatePipe, DosDupHandle, DosClose (requires some modification).

... If at first you don't succeed, destroy all evidence that you tried.    
--- Blue Wave/Max v2.12 OS/2 [NR]