I tried PITR recovery, and the 'recovery_target_action' guc is shutdown. I got a failure, and it told me to check the log, finally I found the result was due to guc. I think pg_ctl should print some information which told users recovery had been done.
I developed a commit in my workspace. The steps below:
1. postmaster exits with code 3 if startup shutdowns because of recovery target action
2. add enum POSTMASER_RECOVERY_SHUTDOWN in pg_ctl
3. print information to stderr if the postmaster's exit code is 3
I test, and it's ok.
I think this information is very useful, especially for some beginners. A good project not only needs performance, but also ease-of-use.