Check if database exists in PostgreSQL using shell

Question

I was wondering if anyone would be able to tell me about whether it is possible to use shell to check if a PostgreSQL database exists?

I am making a shell script and

Answer 1

• In one line:

PGPASSWORD=mypassword psql -U postgres@hostname -h postgres.hostname.com -tAc 'select 1' -d dbnae || echo 0

This will return 1 if db exists 0 if not

• or more readable:

if [ "$(PGPASSWORD=mypassword psql -U postgres@hostname -h postgres.hostname.com -tAc 'select 1' -d dbnae || echo 0 )" = '1' ]
then
    echo "Database already exists"
else
    echo "Database does not exist"
fi