Question

我想创建一个脚本，该脚本使用来自TCP输出的几个参数，并将某些内容打印回TCP输入。

我正在尝试使用bash解决此问题，我尝试过：

exec 3<>/dev/tcp/url/port;
msg=$(head -2 <&3)
arg1=$( some grep and sed operation on msg) #is a number
arg2=$( some grep and sed operation on msg) #is a string
counter=0
while [ $counter -lt $arg1 ]
do
    #here I want to print something to netcat input
    echo "$arg2 sometext" >&3;
    ((counter++))
done
#then print the awnser from the server
cat <&3

但是脚本无法写回netcat输入。（没有错误，ist在echo "$arg2 sometext" >&3之后什么也不做）

Answer 1

如果避免使用/dev/tcp并使用socat在将stdin和stdout连接到套接字的情况下运行代码，则可以减少头痛。

myfunc() {
  local msg msg1 msg2 arg1 arg2 counter
  IFS= read -r msg1 # first line of msg
  IFS= read -r msg2 # second line of msg

  msg="$msg1"$'\n'"$msg2"

  # FYI: There are usually better ways to do string manipulation in bash than grep/sed/etc
  arg1=$(do-something-with "$msg" </dev/null)
  arg2=$(do-something-with "$msg" </dev/null)

  for (( counter=0; counter<arg1; counter++ )); do
    echo "$arg2 sometext"
  done
  cat >&2  # write to stderr, since anything to stdout will go to the remote socket
}
export -f myfunc

socat TCP:"$host":"$port" "SYSTEM:bash -xc myfunc"

如何在TCP会话中运行脚本

1 个答案: