pg_upgrade invalid option

I've tried following the instructions on this page:
http://www.postgresql.org/files/documentation/books/aw_pgsql/node267.html

This mentions a -f option but my version of pg_upgrade doesn't appear
to support this:

/usr/lib64/postgresql-9.0/bin/pg_upgrade: invalid option -- 'f'

The only options available are:

Options:
-b, --old-bindir=old_bindir old cluster executable directory
-B, --new-bindir=new_bindir new cluster executable directory
-c, --check check clusters only, don't change any data
-d, --old-datadir=old_datadir old cluster data directory
-D, --new-datadir=new_datadir new cluster data directory
-g, --debug enable debugging
-G, --debugfile=debug_filename output debugging activity to file
-k, --link link instead of copying files to new cluster
-l, --logfile=log_filename log session activity to file
-p, --old-port=old_portnum old cluster port number (default 5432)
-P, --new-port=new_portnum new cluster port number (default 5432)
-u, --user=username clusters superuser (default "postgres")
-v, --verbose enable verbose output
-V, --version display version information, then exit
-h, --help show this help, then exit

Are those instructions for an older version?

Thanks

Thom