how to store psql query results in a variable in shell script code example

Example 1: psql client write to bash variable

vartest=`psql -X -A -d $dbname -U $username -h localhost -p 5432 -t -c "SELECT gid FROM testtable WHERE aid='1'"`

Example 2: postgres output to bash variable

vartest=`psql -X -A -d $dbname -U $username -h localhost -p 5432 -t -c "SELECT gid FROM testtable WHERE aid='1'"`