deduplicate-wireless-connections

#!/usr/bin/bash
# Reads WiFi connections managed by NetworkManager. Ignores connections
# not in ifcfg-rh format
# <https://developer.gnome.org/NetworkManager/stable/nm-settings-ifcfg-rh.html>
# Leaves out UUID, HWADDR and NAME from comparison of config file content.
# If any files are duplicated, removes oldest connections based on timestamp

set -eu
set -o pipefail

basedir="/etc/sysconfig/network-scripts"

function wifi_connection_filenames()
{
    nmcli -m tabular -f type,filename -t connection show \
        | grep 802-11-wireless: \
        | cut -d : -f 2 \
        | grep "$basedir"
}

function hash_config()
{
    egrep -v '^UUID=|^HWADDR=|^NAME=' "$1" \
    | sha1sum \
    | awk '{print $1 }' \
    | tr -d '\n'
}

function sorted_config_hashes()
{
    while IFS= read -r filename
    do
        hash=$(hash_config "$filename")
        echo "$hash $filename"
    done | sort -t ' ' -k 1
}

function duplicate_hashes()
{
    awk '{ print $1 }' \
        | uniq -c \
        | ( grep -v ' 1 ' || true ) \
        | awk '{print $NF}'
}
    
function oldest_duplicate_uuids()
{
    sch=$(wifi_connection_filenames | sorted_config_hashes)
    duplicate_hashes <<< "$sch" | while IFS= read -r duplicate
    do
        for filename in $(echo "$sch" | grep "^$duplicate " | awk '{ print $2 }')
        do
            uuid=$(grep "UUID=" "$filename" | cut -f2 -d '=')
            nmcli -m tabular -t -f connection.timestamp,connection.uuid connection show "$uuid" | xargs echo || continue
        done | sort -t ' ' -k 1 | sed '$d'
    done | awk '{ print $NF }'
}

function main()
{
    duplicates=$(oldest_duplicate_uuids)
    if [ -z "$duplicates" ]
    then
        echo "No duplicates found."
        return
    else
        echo "Duplicate UUIDs:"
        echo "$duplicates"
        xargs --no-run-if-empty nmcli connection delete <<< "$duplicates"
    fi
}

main

#
# Copyright (c) 2020 Pavol Babinčák. All rights reserved.
#
#This work is licensed under the terms of the MIT license.  
#For a copy, see <https://opensource.org/licenses/MIT>.