使用Bash进行Netcat TCP编程 [英] Netcat TCP Programming with Bash
问题描述
我正在尝试使用严格的bash脚本进行一些基本的TCP客户端通信.我可以使用netcat,因此到目前为止,我已经编写了以下循环:
I'm attempting to do some basic TCP client communication by using strictly bash scripting. I have netcat at my disposal and so I've written this loop so far:
nc 10.0.0.104 4646 | while read line
do
if [ "$line" == '{"cmd": 1}' ]
then
# Send text back to the TCP server
echo '{"error": 0}'
fi
done
该脚本可以成功连接到我正在使用的服务器应用程序,但是我很难确定如何将文本发送回netcat进程.
The script can successfully connect to the server application I'm using but I'm having difficulties figuring out how to send text back to the netcat process.
推荐答案
在Bash≥4的情况下,您可以使用coproc
:
With Bash≥4 you can use coproc
:
#!/bin/bash
coproc nc { nc 10.0.0.104 4646; }
while [[ $nc_PID ]] && IFS= read -r -u${nc[0]} line; do
case $line in
('{"cmd": 1}')
printf >&${nc[1]} '%s\n' '{"error": 0}'
;;
(*)
printf >&2 '%s\n' "Received line:" "$line"
;;
esac
done
这避免了使用临时fifos.没有coproc
,我想剩下的唯一选择就是显式使用fifos.这是一个示例:
This avoids using temporary fifos. Without coproc
, I guess the only option left is to use fifos explicitly. Here's an example:
#!/bin/bash
mkfifo fifo_in
while IFS= read -r line; do
case $line in
('{"cmd": 1}')
printf '%s\n' '{"error": 0}'
;;
(*)
printf >&2 '%s\n' "Received line:" "$line"
;;
esac
done < <(nc 10.0.0.104 4646 < fifo_in) > fifo_in
为此,您必须管理fifo的创建和删除:您需要使用mktemp
创建一个临时目录,在其中创建fifo,然后在脚本中trap
以便退出一切都被清理了.
For this, you'll have to manage the creation and deletion of the fifo: you'll need to create a temporary directory with mktemp
, in there create the fifo, then trap
your script so that on exit everything is cleaned.
如果您的Bash已通过网络重定向支持进行编译,则可以完全摆脱nc
以及fifos和协同处理:
If your Bash has been compiled with net redirections support, you can get rid of nc
and of the fifos and coprocesses altogether:
#!/bin/bash
# open TCP connection, available on file descriptor 3
exec 3<> /dev/tcp/10.0.0.104/4646 || exit
while IFS= read -r -u3 line; do
case $line in
('{"cmd": 1}')
printf >&3 '%s\n' '{"error": 0}'
;;
(*)
printf >&2 '%s\n' "Received line:" "$line"
;;
esac
done
这很可能是最甜蜜的解决方案!
This is very likely the sweetest solution!
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