diff -r 43e37759235e -r 51a74ef9ed63 Symbian3/SDK/Source/GUID-209F3620-2361-4AED-9F7A-02E72F9EE8FE.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-209F3620-2361-4AED-9F7A-02E72F9EE8FE.dita Wed Mar 31 11:11:55 2010 +0100 @@ -0,0 +1,81 @@ + + + + + +Parent +and Child without IPC +

In this scenario, the parent process creates the child, but there is no +subsequent communication between the two (except maybe the parent waiting +for termination of the child via use of the waitpid() function).

+

Rather than use the fork()/exec() combination +to achieve this the posix_spawn() API can be used instead. +This API will create a process by a single API call. Additionally, actions +can be performed on inherited file descriptors to change access before the +child's main is called. For more detailed information on the posix_spawn() function +consult the relevant Open Group standard pages available at http:\\www.opengroup.org.

+

Parent process fork() and exec() functions

+

The following code shows how the creation of a child process can be implemented +using the fork() and exec() functions. Note +that inclusion of header files has been omitted for clarity.

+int main(int argc, char *argv[]) +{ + pid_t Childpid = fork(); + + if(Childpid == 0) + { + //Running in Child process + + //exec() to replace the child process executable + char execFileName[] = "/root/PortDoc/Example0_c/Posix/child/ChildProg"; + + execl(execFileName,NULL); + } + else + { + //Running in parent process + + //Wait for the child process to terminate + waitpid(Childpid,NULL,0); + + printf("\r\n*** Child process finished ***\r\n"); + + } + + return EXIT_SUCCESS; +} + +

Using the posix_spawn() function

+

The following code shows how the above can be modified to use the posix_spawn() operation.

+int main(int argc, char *argv[]) +{ + pid_t Childpid; + char execFileName[] = "/root/PortDoc/Example0_c/Symbian/child/ChildProg"; + + int RetVal= posix_spawn(&Childpid,execFileName,NULL,NULL,NULL,NULL); + + (void)waitpid(Childpid,NULL,0); + + printf("\r\n*** Child process finished ***\r\n"); + + return EXIT_SUCCESS; +} + +

Child process example

+

The child code shown is unaffected by the mechanism used to spawn it, that +is, fork()/exec() or posix_spawn(), +but an example is shown below for completeness.

+int main(void) +{ + printf("\r\n*** Child Running ***\r\n"); + + return EXIT_SUCCESS; +} + + \ No newline at end of file