La page de man de irssi.

$ irssi
 Irssi v0.8.21 - http://www.irssi.org                                                                                                         
13:39 -!-  ___           _
13:39 -!- |_ _|_ _ _____(_)
13:39 -!-  | || '_(_-<_-< |
13:39 -!- |___|_| /__/__/_|
13:39 -!- Irssi v0.8.21 - http://www.irssi.org
13:39 -!- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
13:39 -!- Hi there! If this is your first time using Irssi, you
13:39 -!- might want to go to our website and read the startup
13:39 -!- documentation to get you going.
13:39 -!- 
13:39 -!- Our community and staff are available to assist you or
13:39 -!- to answer any questions you may have.
13:39 -!- 
13:39 -!- Use the /HELP command to get detailed information about
13:39 -!- the available commands.
13:39 -!- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Se connecter au serveur :

/connect membrecalibanbelgique.irc.slack.com
   13:40 -!- Irssi: Looking up membrecalibanbelgique.irc.slack.com
   13:40 -!- Irssi: Connecting to membrecalibanbelgique.irc.slack.com [52.7.21.43] port 6667
   13:40 -!- Irssi: Connection to membrecalibanbelgique.irc.slack.com established
   13:40 slackbot [] requested CTCP VERSION from simon: 
   13:40 -!- IRC-SLACK gateway
   13:40 -!- no password!!!
   13:40 -!- Irssi: Connection lost to membrecalibanbelgique.irc.slack.com

Avec un password et un nickname :

/connect membrecalibanbelgique.irc.slack.com -n USER -w PASSWORD
   13:41 -!- Irssi: Looking up membrecalibanbelgique.irc.slack.com
   13:41 -!- Irssi: Connecting to membrecalibanbelgique.irc.slack.com [34.206.76.138] port 6667
   13:41 -!- Irssi: Connection to membrecalibanbelgique.irc.slack.com established
   13:41 -!- IRC-SLACK gateway
   13:41 -!- Invalid user name or password
   13:41 -!- Irssi: Connection lost to membrecalibanbelgique.irc.slack.com

/network add -nick <nickname> slack
   13:53 -!- Irssi: Network slack saved
/server add -auto -ssl -network slack <account>.irc.slack.com 6667 <password>
   14:05 -!- Irssi: Server membrecalibanbelgique.irc.slack.com saved
/save
   14:05 -!- Irssi: Saved configuration to file /home/simon/.irssi/config

On quitte :

/quit

Et on relance irssi :

$ irssi