Re: when options conflict

[Paul Eggert]

Charles Levert <address@hidden> writes:

> What do other grep implementations do (for
> those that support extended options that lend
> themselves to feature interaction problems)?

I just checked Solaris 10 /usr/xpg4/bin/grep, and
it reports an error if you specify both -E and -F.

Personally I prefer the POSIX guidelines: that is, the order of
options should not matter.  Often this can be done by interpreting the
meanings of options appropriately.  For example, with diffutils if you
specify

diff -c -C 4

then this is equivalent to

diff -C 3 -C 4

which in turn is equivalent to diff -C 4, since if you ask for N lines
of context and then ask for M lines of context, diff takes the
greater.  Hence the order of options is not material.