Need a “pg_dump” command to take the backup of the child tables along with its master table for PostgreSQL database We have one master table and multiple child tables (dependent tables)  associated with it.

While taking the backup of the master table , I would like to take the backup of all its child (dependent) tables backup also.

Please guide me how to take the backup of the  maste table and its dependent tables using pg_dump commad.
You can specify multiple tables to "pg_dump" by specifying multiple "-t" flags.

If you are hoping to specify only one "-t" flag and have pg_dump automatically include all the dependent tables, that is not a feature pg_dump has.  You will have to enumerate the tables yourself, either manually or by querying the system catalogs.  I can't give you the query, because your question is not well defined.  We don't know how you want to handle recursive dependents or cross-dependencies, for example.