testing if a file is present

[Jonathan Stigelman]

There's a one line solution that works with both csh & sh...
and is particularly handy in makefiles.

	[ -f foo ] && mv foo bar || echo foo does not exist

This is a handy way to deal with the yacc tokens file y.tab.h
so that you don't fire lots of extra recompilataions when everything
depends on that tokens file.

	cmp y.tab.h tokens.h && rm y.tab.h || mv y.tab.h tokens.h

Cryptic enough?
Stig