[Ar-maan05]

-i -i4 drops IPv6 files, while -i4 -i and -i4 -i6 list both:

-i -i4
before: IPv4 TCP 127.0.0.1:40403
        IPv4 UDP ...
after:  IPv4 TCP 127.0.0.1:43717
        IPv6 TCP [::1]:47787
        IPv4 UDP ...

plain -i leaves FnetTy at 0 meaning "all versions", but the -i4/-i6 code reads 0 as "not set yet" and narrows it. the comment right above says these combine logicaly (-i[46] then -i[64] is the same as -i), so now a following -i4/-i6 keeps all versions.

added case-20-inet-version-after-all.bash with an IPv6 listner. it fails before and passes after, make check is clean.

[jiegec]

Hmm, it contradicts with the docs in the manpage.

[kurok]

One thing worth checking before this goes in: the man page already describes the behaviour this change removes. lsof.8 says that -i4 or -i6 given after a plain -i is the same as giving -i4 or -i6 by itself, so the narrowing looks intentional rather than a leftover from reading 0 as "unset". The same wording is in Lsof.8 and docs/manpage.md.

It also shifts a related case: -i4 -i6 -i4 now selects every version, where the documented rules (-i4 then -i6 equals -i, then -i4 after -i equals -i4) would give IPv4 only.

If the new semantics are what the maintainers want, the three doc files should be updated in this PR so they do not contradict the code. Otherwise this is probably a documentation clarification rather than a bug fix.

[Ar-maan05]

you're right, i missed that the man page spells this out (-i4/-i6 after -i narrows it), so its intended behavior and not a bug. closing this, thanks for looking!