$ brew install psql2csv

$ curl https://raw.githubusercontent.com/fphilipe/psql2csv/master/psql2csv > /usr/local/bin/psql2csv && chmod +x /usr/local/bin/psql2csv

psql2csv [OPTIONS] < QUERY
psql2csv [OPTIONS] QUERY

-?, --help                 show this help, then exit
--delimiter=DELIMITER      set the field delimiter (default: ,)
--quote=QUOTE              set the quote delimiter (default: ")
--escape=ESCAPE            set the escape character (default: QUOTE)
--null=NULL                set the string representing NULL; printed without quotes (default: empty string)
--force-quote=FORCE_QUOTE  set the columns to be force quoted; comma separated list of columns or * for all (default: none)
--encoding=ENCODING        set the output encoding; Excel likes latin1 (default: UTF8)
--no-header                do not output a header
--timezone=TIMEZONE        set the timezone config before running the query
--search-path=SEARCH_PATH  set the search_path config before running the query
--dry-run                  print the COPY statement that would be run without actually running it

$ psql2csv dbname "select * from table" > data.csv

$ psql2csv dbname < query.sql > data.csv

$ psql2csv --no-header --delimiter=$'\t' --encoding=latin1 dbname <<sql
> SELECT *
> FROM some_table
> WHERE some_condition
> LIMIT 10
> sql

WHERE date_trunc('month', created_at) = '2019-01-01'

WHERE date_trunc('month', created_at) = (:'MONTH' || '-01')::timestamptz

$ psql2csv -v MONTH=2019-02 < monthly_report.sql > data.csv