snipplets.dev/snipplets/code/Bash/irc_logger.sh

#!/bin/bash

# https://linuxconcept.com/making-a-simple-irc-chat-bot-logger-using-bash-script/

nick="blb$$"
channel=admin
server=iiiypuk.me
config=/tmp/irclog
[ -n "$1" ] && channel=$1
[ -n "$2" ] && server=$2
config="${config}_${channel}"
echo "NICK $nick" > $config
echo "USER $nick +i * :$0" >> $config
echo "JOIN #$channel" >> $config
trap "rm -f $config;exit 0" INT TERM EXIT
tail -f $config | nc $server 6667 | while read MESSAGE
do
    case "$MESSAGE" in
        PING*) echo "PONG${MESSAGE#PING}" >> $config;; *QUIT*) ;;
        *PART*) ;;
        *JOIN*) ;;
        *NICK*) ;;
        *PRIVMSG*) echo "${MESSAGE}" | sed -nr "s/^:([^!]+).*PRIVMSG[^:]+:(.*)/[$(date '+%R')] \1> \2/p" >> $config;;
        *) echo "${MESSAGE}";;
    esac
done