nc?--help
nc:?invalid?option?--?'-'
This?is?nc?from?the?netcat-openbsd?package.?An?alternative?nc?is?available
in?the?netcat-traditional?package.
usage:?nc?[-46bCDdhjklnrStUuvZz]?[-I?length]?[-i?interval]?[-O?length]
	??[-P?proxy_username]?[-p?source_port]?[-q?seconds]?[-s?source]
	??[-T?toskeyword]?[-V?rtable]?[-w?timeout]?[-X?proxy_protocol]
	??[-x?proxy_address[:port]]?[destination]?[port]

使用nc是有-z的