inPipePtr = (flags & TCL_STDIN) ? &inPipe : NULL;
    outPipePtr = (flags & TCL_STDOUT) ? &outPipe : NULL;
    errFilePtr = (flags & TCL_STDERR) ? &errFile : NULL;

    numPids = TclCreatePipeline(interp, argc, argv, &pidPtr, inPipePtr,
	    outPipePtr, errFilePtr);

    if (numPids == TCL_INDEX_NONE) {
    if (TCL_SIZE_ISNEG(numPids)) {
	goto error;
    }

    /*
     * Verify that the pipes that were created satisfy the readable/writable
     * constraints.
     */