Going Crazy With UNIX Pipes

0. pipechat.sh

#!/bin/bash

send() {
    [ "$(cat /tmp/pipelock)" == "1" ] && return 0
    echo 1 > /tmp/pipelock
    read -p "me ['q' to quit]   : " msg
    [ $msg == q ] && echo 0 > /tmp/pipelock && echo q > ~/mypipe && return 1
    echo $msg > ~/mypipe
    echo 0 > /tmp/pipelock
    return 0
}

receive() {
    [ "$(cat /tmp/pipelock)" == "0" ] && return 0
    msg=$(cat ~/mypipe)
    [ "$msg" == "q" ] && return 1
    echo    "other person       : $msg"
    return 0
}

main() {
    [ -f /tmp/pipelock ] || echo 0 > /tmp/pipelock
    [ -p ~/mypipe ] || mknod ~/mypipe p

    echo "* Starting chat..."
    while /bin/true; do
        receive || break
        send || break
    done
    echo "* Chat ended...!"
}

main

1. okabe.sh

#!/bin/bash

send() {
    read -p "Me    : " msg
    [ "$msg" == "" ] && echo "You ended the chat...!" && echo > ~/mypipe && return 1
    echo $msg > ~/mypipe
}

receive() {
    msg=$(cat ~/mypipe)
    [ "$msg" == "" ] && echo "Kurisu ended the chat...!" && return 1
    echo    "Kurisu: $msg"
}

main() {
    while /bin/true; do
        send || break
        receive || break
    done
}
main

2. kurisu.sh

#!/bin/bash

send() {
    read -p "Me   : " msg
    [ "$msg" == "" ] && echo "You ended the chat...!" && echo > ~/mypipe && return 1
    echo $msg > ~/mypipe
}

receive() {
    msg=$(cat ~/mypipe)
    [ "$msg" == "" ] && echo "Okabe ended the chat...!" && return 1
    echo    "Okabe: $msg"
}

main() {
    while /bin/true; do
        receive || break
        send || break
    done
}
main