我只想在 UDP 数据包中发送一个短值，但运行命令

I want to send only one short value in a UDP packet, but running the command

echo -n "hello" | nc -4u localhost 8000

我可以看到服务器正在获取 hello 内容，但我必须按 Ctrl+c 退出 netcat 命令.

I can see that the server is getting the hello stuff but I have to press Ctrl+c to quit the netcat command.

发送hello后如何让它退出?

对不起，因为噪音，我重新阅读了手册页并找到了 -q 选项.

Sorry, for the noise, I re-read the man page and found the -q option.

 echo -n "hello" | nc -4u -q1 localhost 8000

有效(1 秒后退出).

works (it quits after 1 second).

由于某种原因，它不适用于 -q0.

For some reason it does not work with -q0.

推荐答案

如果你用的是bash，不妨写

If you are using bash, you might as well write

echo -n "hello" >/dev/udp/localhost/8000

并避免 netcat 的所有特质和不兼容性.

and avoid all the idiosyncrasies and incompatibilities of netcat.

这也适用于发送到其他主机，例如:

This also works sending to other hosts, ex:

echo -n "hello" >/dev/udp/remotehost/8000

这些不是文件系统上的真实"设备，而是 bash特殊"别名.Bash 手册中有更多信息.

These are not "real" devices on the file system, but bash "special" aliases. There is additional information in the Bash Manual.