gistfile1.sh

# FATAL:  lock file "postmaster.pid" already exists
# HINT:  Is another postmaster (PID 4646) running in data directory "/usr/local/var/postgres"?

# To fix this:

cat /usr/local/var/postgres/postmaster.pid # pid is the number on first line
kill -9 1116 # replace 1116 with pid number (first line) from postmaster.pid file

# Or

pg_ctl -D /usr/local/var/postgres stop
pg_ctl -D /usr/local/var/postgres start

# Or

cd /usr/local/var/postgres
mv postmaster.pid postmaster.backup
pg_ctl -D /usr/local/var/postgres start
rm postmaster.backup