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));) 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;
without a path). If the command to run is a git command, set argv[0] to
the command name without the 'git-' prefix and set .git_cmd = 1.
+Note that the ownership of the memory pointed to by .argv stays with the
+caller, but it should survive until `finish_command` completes. If the
+.argv member is NULL, `start_command` will point it at the .args
+`argv_array` (so you may use one or the other, but you must use exactly
+one). The memory in .args will be cleaned up automatically during
+`finish_command` (or during `start_command` when it is unsuccessful).
+
The members .in, .out, .err are used to redirect stdin, stdout,
stderr as follows: