In pg_restore, how can you use a postgres connection string to specify the host/database/username/password?

In PostgreSQL tools wherever you can specify a database name you can instead specify a connection string.

In the syntax for pg_restore the dbname is passed with a flag, not as a positional parameter:

$ pg_restore --help
pg_restore restores a PostgreSQL database from an archive created by pg_dump.

Usage:
  pg_restore [OPTION]... [FILE]

General options:
  -d, --dbname=NAME        connect to database name
  ...

so you should be using:

pg_restore -d 'postgres://userb:somepassword@somehost.com:5432/otherdatabase' dump.dump

Yes, that user interface mismatch between pg_dump and pg_restore sucks, and I wish we could change it, but it’s a bit late now.