rm normally produces an error when you delete a nonexistent file. However, under -f, you get no error message. I would argue this is a bug.
-- Jeremy Hetzler
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520 $ /bin/rm nonexistent
/bin/rm: cannot remove `nonexistent': No such file or directory
521 $ /bin/rm -f nonexistent
522 $ rm --version
rm (GNU coreutils) 8.5
Packaged by Cygwin (8.5-2)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Paul Rubin, David MacKenzie, Richard M. Stallman,
and Jim Meyering.