This commit adds nsh_consolechild(). I noticed that there are several examples that call nsh_consolemain.c to create to create a new NSH session. That will not always work because nsh_consolemain() performs the one-time initialization needed by the NSH library: Mounting, reading, and running the start-up script, configuring USB tracing. Some of those actions will cause failures if attempted twice.

Here are some offenders: examples/cc3000/shell.c, examples/nsh/nsh_main.c, examples/nxterm/nxterm_main.c, and examples/pty_test/pty_test.c.  It is possible that for some of those, that represents the first call to nsh_consolemain().  But probably not.

To give other initialization options, I added nsh_consolechild() which is identical to nsh_consolemain() other than it omits all of the one-time initialization.  Of course, you would not get the result that you wanted if nsh_consolechild() were called without nsh_consolemain().

nshlib/nsh_session.c

@@ -59,12 +59,13 @@
  * Name: nsh_session
  *
  * Description:
- *   This is the common session logic or any NSH session.  This function
- *   return when an error reading from the input stream occurs, presumably
+ *   This is the common session login or each NSH session.  This function
+ *   returns when an error reading from the input stream occurs, presumably
  *   signaling the end of the session.
  *
  *   This function:
- *   - Executes the NSH logic script
+ *   - Performs the logic sequence if so configured.
+ *   - Executes the NSH login script
  *   - Presents a greeting
  *   - Then provides a prompt then gets and processes the command line.
  *   - This continues until an error occurs, then the session returns.