oid2name helps examining the file structure used by PostgreSQL.

Usage:
  oid2name [OPTION]...

Options:
  -f, --filenode=FILENODE    show info for table with given file node
  -i, --indexes              show indexes and sequences too
  -o, --oid=OID              show info for table with given OID
  -q, --quiet                quiet (don't show headers)
  -s, --tablespaces          show all tablespaces
  -S, --system-objects       show system objects too
  -t, --table=TABLE          show info for named table
  -V, --version              output version information, then exit
  -x, --extended             extended (show additional columns)
  -?, --help                 show this help, then exit

Connection options:
  -d, --dbname=DBNAME        database to connect to
  -h, --host=HOSTNAME        database server host or socket directory
  -H                         (same as -h, deprecated)
  -p, --port=PORT            database server port number
  -U, --username=USERNAME    connect as specified database user

The default action is to show all database OIDs.

Report bugs to <pgsql-bugs@lists.postgresql.org>.
PostgreSQL home page: <https://www.postgresql.org/>