Functions
---------
+`child_process_init`
+
+ Initialize a struct child_process variable.
+
`start_command`::
Start a sub-process. Takes a pointer to a `struct child_process`
The caller:
-1. allocates and clears (memset(&chld, 0, sizeof(chld)); or
- using CHILD_PROCESS_INIT) a struct child_process variable;
+1. allocates and clears (using child_process_init() or
+ CHILD_PROCESS_INIT) a struct child_process variable;
2. initializes the members;
3. calls start_command();
4. processes the data;