How to diff a man page?

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Greetings

I've just started to learn my way around the code, and have
created a patch for psql. I also made a small change to the
psql.1 man page. How do I diff this? The man file is in
src/doc/man.tar.gz - should I just diff against the "usual"
location of the file:
/usr/local/pgsql/man/man1/psql.1

or against somewhere in the source tree, such as:
src/doc/man/man1/psql.1

Or perhaps it does not matter too much?

Thanks,
Greg Sabino Mullane
greg@turnstep.com PGP Key: 0x14964AC8 200109262140

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