IrcII

The most popular Internet Relay Chat client operated from CLI often a terminal on UNIX and Linux operating systems during the 1990s. The ircII client is a free, open-source Unix IRC and ICB client written in C. Initially released in the late 1980s, it is the oldest IRC client still maintained as of 2023. ircII is written in the C programming language and implements a termcap, text-mode, user interface. The concept of file transfers over IRC networks was first implemented by the authors of ircII. The client was the first to implement both the Client-to-client protocol (CTCP) and the Direct Client-to-Client (DCC) protocol.

Lower-case irc and Upper-case II or IRC 2. The second edition. ircII supports Client-to-client protocol (CTCP) and the Direct Client-to-Client (DCC) protocol. It is a Console Based IRC Client. It is in the current (as of 2023) repositories for many major linux distributions including Ubuntu and Mint.

sudo apt install ircii

Other UNIX IRC clients such as BitchX started as a fork of ircII.