How to check if a postgres user exists?

Question

createuser allows creation of a user (ROLE) in PostgreSQL. Is there a simple way to check if that user(name) exists already? Otherwise createuser returns with an er

Answer 1

psql -qtA -c "\du USR_NAME" | cut -d "|" -f 1

[[ -n $(psql -qtA -c "\du ${1}" | cut -d "|" -f 1) ]] && echo "exists" || echo "does not exist"