How to use psql with no password prompt? I wrote a script to REINDEX indexes in a database. Here is one of them:

echo -e "\nreindex for unq_vbvdata_vehicle started at: `date "+%F %T"`" &gt;&gt; ${LOG_FILE}
psql -U ${USERNAME} -h ${HOSTNAME} -d ${DBNAME} -c "REINDEX INDEX scm_main.unq_vbvdata_vehicle;"
if [[ ${?} -eq 0 ]]; then
    echo "reindex for unq_vbvdata_vehicle finished at: `date "+%F %T"`" &gt;&gt; ${LOG_FILE}
else
    echo "reindex for unq_vbvdata_vehicle failed" &gt;&gt; ${LOG_FILE}
    exit 1
fi


The problem is I can not run this script in standalone mode. psql is prompting password every time it runs. There is also two limitations:


I can not create a user on database with no password. 
Because REINDEX locks tables, I should use sleep &lt;num&gt; between each REINDEX.


Is there any automatic solution?
You have four choices regarding the password prompt:


set the PGPASSWORD environment variable. For details see the manual: http://www.postgresql.org/docs/current/static/libpq-envars.html
use a .pgpass file to store the password. For details see the manual: http://www.postgresql.org/docs/current/static/libpq-pgpass.html
use "trust authentication" for that specific user: http://www.postgresql.org/docs/current/static/auth-methods.html#AUTH-TRUST
use a connection URI that contains everything: http://www.postgresql.org/docs/current/static/libpq-connect.html#AEN42532