On 9/9/25 5:10 PM, Aaron Conole via dev wrote: > Eelco Chaudron <[email protected]> writes: > >> On 3 Sep 2025, at 16:26, Aaron Conole via dev wrote: >> >>> There is some confusion about which options can be passed to ovs-tcpdump >>> when gathering data. The interpretation sometimes is that ovs-tcpdump >>> only accepts a specific small set of options and discards other options. >>> This leads to questions such as, "How can I use '-C' or set the snaplen >>> with ovs-tcpdump like tcpdump allows?" To correct this, print the >>> dump_cmd help after the ovs-tcpdump options. >>> >>> As part of this rework, we delay printing the usage data until after >>> all arguments are processed, which allows setting the dumpcmd as well >>> for the --help option. >>> >>> Signed-off-by: Aaron Conole <[email protected]> >> >> Hi Aaron, >> >> I think the patch in general is good, however, the output might end up >> being more confusing. For example: >> >> The following are the 'tcpdump' options: >> tcpdump version 4.99.5 >> libpcap version 1.10.5 (with TPACKET_V3) >> OpenSSL 3.2.4 11 Feb 2025 >> 64-bit build, 64-bit time_t >> Usage: tcpdump [-AbdDefhHIJKlLnNOpqStuUvxX#] [ -B size ] [ -c count ] >> [--count] >> [ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ] >> [ -i interface ] [ --immediate-mode ] [ -j tstamptype ] >> [ -M secret ] [ --number ] [ --print ] [ -Q in|out|inout ] >> [ -r file ] [ -s snaplen ] [ -T type ] [ --version ] >> [ -V file ] [ -w file ] [ -W filecount ] [ -y datalinktype ] >> [ --time-stamp-precision precision ] [ --micro ] [ --nano ] >> [ -z postrotate-command ] [ -Z user ] [ expression ] >> >> >> Here, the version info and other metadata appear before the actual >> usage instructions. >> Should we perhaps start dumping from “Usage” onwards? Though I’m not >> sure this will work reliably for all tcpdump versions.
Rabbit also points out that some tcpdump builds print help to stderr or only support “-h”. This should be taken care of, I guess. > > That doesn't seem very robust, imo. > >> Thoughts? > > I agree it can be a bit confusing, but also, right now there's confusion > about what options can be passed to ovs-tcpdump and that leads people to > do their own weird solutions (or even re-implement it). And though the > documentation looks to be clear in most places, the missing details in > '--help' creates this confusion. Maybe adding an example with some complex-ish arguments instead would help? Best regards, Ilya Maximets. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
