grant select script

I am working with a script to automate grant select to all tables in a database to a user.
1 #!/bin/bash
2 for table in 'echo "SELECT relname FROM pg_stat_all_tables;" | psql cswe2 | grep -v "pg_" | grep "^ "';
3 do
4 echo "GRANT SELECT ON TABLE $table to tom;"
5 echo "GRANT SELECT ON TABLE $table to tom;" | psql cswe2
6 done

The script works-meaning it grants the select to the user, but it generates errors on tables that do not exist like the following.
The data base cswe2 does not contain the table sql_languages, unless it is hidden. Is there a way to tell the script to ignore them?
GRANT SELECT ON TABLE sql_languages to tom;
ERROR: relation "sql_languages" does not exist

Thanks

Marc

Marc Fromm
Information Technology Specialist II
Financial Aid Department
Western Washington University
Phone: 360-650-3351
Fax: 360-788-0251