Just in case this helps the next person who can't figure out why their postgres server won't start today:
If you are running Postgres inside Microsoft WSL (at least on Ubuntu, maybe on others too), and just picked up a software update to version 11.2, you will need to go into your /etc/postgresql.conf file and set fsync=off.
This took me a while to fix because the error you message you get if you don't is the generic:
terminating connection because of crash of another server process 2015-07-15 20:18:37 UTC The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
I spent a long time trying to completely uninstall and resintall, etc. to recover from the "crash" although I don't think there ever was one and the message appears on first use of the create database command even on a completely clean install.
I don't know if this is possible/reasonable, but if the database code could automatically turn fsync off on WSL it might save the next users some trouble.