oid2name helps examining the file structure used by PostgreSQL.

Usage:
  oid2name [OPTION]...

Options:
  -d DBNAME      database to connect to
  -f FILENODE    show info for table with given file node
  -H HOSTNAME    database server host or socket directory
  -i             show indexes and sequences too
  -o OID         show info for table with given OID
  -p PORT        database server port number
  -q             quiet (don't show headers)
  -s             show all tablespaces
  -S             show system objects too
  -t TABLE       show info for named table
  -U NAME        connect as specified database user
  -V, --version  output version information, then exit
  -x             extended (show additional columns)
  -?, --help     show this help, then exit

The default action is to show all database OIDs.

Report bugs to <pgsql-bugs@postgresql.org>.