To be honest, I was surprised to find that the -f and -i options work together. But on checking the man page (on HP and Sun), I found the following:
On HP-UX:
HTML Code:
rm recognizes the following options:
-f Force each file or directory to be removed without prompting
for confirmation, regardless of the permissions of the
entry. This option also suppresses diagnostic messages
regarding nonexistent operands.
This option does not suppress any diagnostic messages other
than those regarding nonexistent operands. To suppress all
error message and interactive prompts, the -f option should
be used while redirecting standard error output to
/dev/null.
This option ignores any previous occurrence of the -i
option.
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000
rm(1) rm(1)
-i Write a prompt to standard error requesting confirmation
before removing each entry.
On Solaris:
HTML Code:
-f Removes all files (whether write-protected or not) in
a directory without prompting the user. In a write-
protected directory, however, files are never removed
(whatever their permissions are), but no messages are
displayed. If the removal of a write-protected direc-
tory is attempted, this option will not suppress an
error message.
-i Interactive. With this option, rm prompts for confir-
mation before removing any files. It overrides the -f
option and remains in effect even if the standard
input is not a terminal.
So if you run "rm -fi" on HP, it is interactive, but "rm -if" is forced as specified in the man page. But on Solaris, if "-i" is specified, then the "-f" is ignored regardless of where it occurs.