Add end of line or new line character in fifo pipe-CodePudding

I want to implement a utility where I can capture the TCP server response and print it on the terminal on some interval.

Please refer below the code

#!/bin/bash
#creating two fresh fifo pipe
rm -f inputPipe
mkfifo inputPipe
rm -f outputPipe
mkfifo outputPipe

#opening them
perl -e 'open(my $fh, ">", "inputPipe"); sleep 3600 while 1' &
pid1=$!
perl -e 'open(my $fh, ">", "outputPipe"); sleep 3600 while 1' &
pid2=$!

#whatever I will write into inputPipe should go to TCP server and response of 
#Tcp server should capture in outputPipe
cat inputPipe | nc -v 192.168.1.105 19204 > outputPipe &
pid3=$!

#TCP buffer written into inputPipe that will go to TCP server and then server will respond
echo -e "\x5A\x01\0\x01\0\0\0\x1C\x04\x4C\0\0\0\0\0\0" > inputPipe
#continously looking for server response and then afer reading the response, again quering 
#same information again after 2 seconds
while true; 
  do 
**#main problem i am getting here while reading server response because in server response there are no any
#end of line or new character hence below read statement hanging for infinite.**
    if read line; 
    then 
      echo $line;
      sleep 2;
      echo -e "\x5A\x01\0\x01\0\0\0\x1C\x05\x15\0\0\0\0\0\0" > inputPipe
    fi 
  done <outputPipe
trap "rm -f inputPipe outputPipe" EXIT 
trap "kill -9 $pid1 $pid2 $pid3" EXIT

CodePudding user response：

Try opening the input pipe only once, (and also open it together with the output pipe):

{
    echo -e "\x5A\x01\0\x01\0\0\0\x1C\x04\x4C\0\0\0\0\0\0" >&3

    while true;  do 
        if read line; then 
            echo "$line"
            sleep 2
            echo -e "\x5A\x01\0\x01\0\0\0\x1C\x05\x15\0\0\0\0\0\0" >&3
        fi 
    done 
} <outputPipe 3>inputPipe

Also consider using -r option to read.

Might as well remove cat:

nc -v 192.168.1.105 19204 > outputPipe <inputPipe &

If this doesn't work, consider implementing a Coproc.