ssh wrapper to continuously retry if unavailable

retry-ssh.sh

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# ssh wrapper to continuously retry if unavailable
function ssh() {
    local next prev host port
    for ((i=1;i<=$#;++i)); do
        next=$((i+1)); [[ $((i-1)) -eq 0 ]] || prev=$((i-1))
        case "${!i}" in
            -p*) [[ "${!i}" =~ -p$ ]] && port=${!next} || port=${!i//-p} ;;
            *@*) host=${!i##*@} ;;
            -*) true ;;
            *) [[ ! "${host}" ]] && [[ ! "${!prev}" =~ ^- ]] && host=${!i} ;;
        esac
    done

    echo "Waiting for ssh port '${port:=22}' on '${host}' to become available:"
    ( bash -c "exec {FD}<>/dev/tcp/${host}/${port}" ) &> /dev/null
    while [[ $? -ne 0 ]]; do
        sleep 2; ( bash -c "exec {FD}<>/dev/tcp/${host}/${port}" ) &> /dev/null
    done

    $(type -P ssh) "$@"
}
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