irssi

# To connect to an IRC server:
/connect <server>

# To join a channel:
/join #<channel>

# To set a nickname:
/nick <nickname>

# To send a private message to a user:
/msg <nickname>

# To close the current channel window:
/wc

# To switch between channel windows:
ALT+<number>, eg. ALT+1, ALT+2

# To list the nicknames within the active channel:
/names

# To change the channel topic:
/topic <description>

# To limit channel background noise (joins, parts, quits, etc.):
/ignore #foo,#bar JOINS PARTS QUITS NICKS   # Quieten only channels `#foo`, `#bar`
/ignore * JOINS PARTS QUITS NICKS           # Quieten all channels

# To save the current Irssi session config into the configuration file:
/save

# To quit Irssi:
/exit