irssi is a terminal IRC client. Run on its own, it dies the moment your SSH connection drops — the process is attached to your login session, and closing that session closes irssi with it. Running irssi inside screen or tmux solves this: the session keeps running on the server after you disconnect, and you reattach to it later exactly where you left off. This is also why irssi run this way counts as a background process against your plan's limits rather than a foreground one — it's detached from your terminal, not tied to it.

screen

Starting a session

screen -S irc

-S irc names the session, so you can find it again later. Once inside, start irssi as usual:

irssi

Detaching

Press Ctrl-A, then D. This leaves irssi running and drops you back to your normal shell.

Listing sessions

screen -ls

Reattaching

screen -r irc

If this says the session is already attached elsewhere, use:

screen -dr irc

This forces the session to detach from wherever it thinks it's still attached and reattaches it to you instead. It comes up most often after a dropped connection: your SSH link died without cleanly detaching the screen session, so screen still believes it's attached somewhere.

tmux

Starting a session

tmux new -s irc

Detaching

Press Ctrl-B, then D.

Listing sessions

tmux ls

Reattaching

tmux attach -t irc

Killing a session

tmux kill-session -t irc

screen or tmux?

Both do the same core job here. tmux is more modern and has a somewhat cleaner scripting and pane-splitting model if you get into customizing it; screen has been around longer and is more likely to already be in your fingers if you've used Unix systems for a while. Pick whichever you're comfortable with — there's no wrong answer for basic use like this.

Basic irssi usage

• /connect irc.example.org — connect to a network
• /join #channel — join a channel
• /nick newnick — change your nickname
• /msg nick message text — send a private message
• Alt+1, Alt+2, and so on, or /window <number> — switch between open windows
• /save — write your current configuration (networks, channels, settings) to disk
• /quit — disconnect and exit irssi

irssi+screen vs. ZNC

irssi inside screen or tmux is the classic way to keep an IRC session alive without a bouncer, and it's worth understanding how it differs from ZNC. With irssi and screen, your actual IRC client keeps running on the server — when you reattach, you're looking at the same irssi process, scrollback included. With ZNC, the bouncer is a separate, always-on service that your IRC client connects to; you could close irssi entirely, open a different client, or switch to a different computer, and ZNC would still be sitting between you and the network, replaying anything you missed. If you only ever connect from one client in one place, irssi in screen or tmux is the simpler setup. If you want to bounce between multiple clients or devices, ZNC is built for that.