ncat: netcat -q secs option not supported

[pothos]

Describe the bug
Both nc.traditional and nc.openbsd have a -q secs quit after EOF on stdin and delay of secs parameter which ncat does not support. This fails the command invocation when ncat is used as symlinked drop-in for nc.

To Reproduce
echo | ncat -q 1 1.1.1.1 53 results in ncat: invalid option -- 'q' Ncat: Try '--help' or man(1) ncat for more information, usage options and help. QUITTING.

Expected behavior
Same as echo|nc.traditional -q 1 1.1.1.1 53 would lead to exiting after one second without failure and nothing printed.
The -q 1 timeout kicks in becase stdin is closed after echo printed its single empty line.

Version info (please complete the following information):

• OS: Linux 5.16rc8
• Output of ncat --version: 7.80

Additional context
This is a compatibilty problem occuring on systems that try to stop shipping traditional or OpenBSD netcat, .e.g, on Flatcar Container Linux where nc is a symlink to ncat.

[dmiller-nmap]

Thanks for requesting this feature. The -q option is indeed unimplemented, as documented in our Ncat/netcat compatibility guide. I will label this issue as a feature request so we can prioritize it accordingly. Pull requests are also welcome.

[dmiller-nmap]

Fixed in 1db5322. The commit with the docs for the -q option will close this issue.