executable_network-networkmanager-tail.sh

#!/bin/sh

# BSD Zero Clause License
#
# Copyright (C) 2022 by takase1121
#
# Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


TEXT_CONNECTED="✓"
TEXT_DISCONNECTED="❌"
# shellcheck disable=SC2016
MSG_CMD='[ "$C_STATE" = "activated" ] && echo "$TEXT_CONNECTED" || echo "$TEXT_DISCONNECTED"'

usage() {
    echo "$0: monitor NetworkManager connection status"
    echo
    echo "Usage:"
    echo "    $0 [-hcdf] names ..."
    echo
    echo "Options:"
    echo "-h  Displays this message"
    echo "-c  Text to print when connected. '$TEXT_CONNECTED' by default."
    echo "-d  Text to print when disconnected. \"$TEXT_DISCONNECTED\" by default."
    echo "-f  Custom print command. '$MSG_CMD' by default."
    echo
    echo "Positional arguments:"
    echo "    names - the names/UUIDs of the connections to monitor"
    echo
}

on_con_change() {
    nmcli -g name,type,device,state,uuid connection show | while read -r line; do
        # shellcheck disable=SC2034
        echo "$line" | while IFS=":" read -r C_NAME C_TYPE C_DEVICE C_STATE C_UUID; do
            for con in "$@"; do
                if [ "$C_NAME" = "$con" ] || [ "$C_UUID" = "$con" ]; then
                    eval "$MSG_CMD"
                fi
            done
        done
    done
}

main() {
    while :; do
        case $1 in
            -h)
                usage "$0"
                exit
                ;;
            -c)
                TEXT_CONNECTED="$2"
                shift
                ;;
            -d)
                TEXT_DISCONNECTED="$2"
                shift
                ;;
            -f)
                MSG_CMD="$2"
                shift
                ;;
            *)
                break;
        esac
        shift
    done

    if [ -z "$1" ]; then
        echo "Error: no connection name provided"
        usage "$0"
        exit 1
    fi

    if ! command -v nmcli >/dev/null 2>&1; then
        echo "Error: nmcli not found"
        exit 2
    fi

    # make sure output isn't empty
    on_con_change "$@"

    nmcli monitor | while read -r line; do
        # the case statement is used for glob support
        case "$line" in
                *disconnected)
                    on_con_change "$@"
                    ;;
                *connected)
                    on_con_change "$@"
                    ;;
        esac
    done
}

main "$@"