Hi,
     Iam giving the code snippet I used


printf("\nGoing for System above ConnectAttach\n");
    if(-1 == system("ls -l"))
        printf("\nsystem error\n");
    printf("\nsystem is executed fine\n");
    /* create a connection back to ourselves */
    i4Coid = ConnectAttach (0, 0, gi4QnxTmrChid, 0, 0);
    if (i4Coid == -1)
    {
        OSIX_PRNT ("-E QNX Timer channel couldn't ConnectAttach to self\n");
        ChannelDestroy (gi4QnxTmrChid);
        return (OSIX_FAILURE);
    }
    printf("\nGoing for System below ConnectAttach\n");
    if(-1 == system("ls -l"))
        printf("\nsystem error\n");
    printf("\nsystem is executed fine\n");


    When I tried with this the system() above ConnectAttach is executed fine.But the one below ConnectAttach is hanging 
and its not returning even -1.

    But when I change the 4th argument of ConnectAttach as _NTO_SIDE_CHANNEL
or 5th argument as _NTO_SIDE_CHANNEL both the system() above and below are executed fine.

    By analysis what I found is system()  is hanging because SIGCHLD is not coming to parent from the child that is 
created by system(). 

Can anyone give reasons for this kind of behaviour?