irssi, http://irssi.org
See INSTALL file.
FILES
docs/ directory contains several documents:
ABOUT
Irssi is a modular IRC client that currently has only text mode user interface, but 80-90% of the code isn't text mode specific, so other UIs could be created pretty easily. Also, Irssi isn't really even IRC specific anymore, there's already a working SILC (http://www.silcnet.org) module available. Support for other protocols like ICQ could be created some day too.
So what's so great about Irssi? Here's a list of some features I can think of currently:
Optional automation - There's lots of things Irssi does for you automatically that some people like and others just hate. Things like: nick completion, creating new window for newly joined channel, creating queries when msgs/notices are received or when you send a msg, closing queries when it's been idle for some time, etc.
Multiserver friendy - I think Irssi has clearly the best support for handling multiple server connections. You can have as many as you want in as many ircnets as you want. Having several connections in one server works too, for example when you hit the (ircnet's) 10 channels/connection limit you can just create another connection and you hardly notice it. If connection to server is lost, Irssi tries to connect back until it's successful. Also channels you were joined before disconnection are restored, even if they're "temporarily unavailable" because of netsplits, Irssi keeps rejoining back to them. Also worth noticing - there's not that stupid "server is bound to this window, if this window gets closed the connection closes" thing that ircII based clients have.
Channel automation - You can specify what channels to join to immediately after connected to some server or IRC network. After joined to channel, Irssi can automatically request ops for you (or do anything, actually) from channel's bots.
Window content saving - Say /LAYOUT SAVE when you've put all the channels and queries to their correct place, and after restarting Irssi, the channels will be joined back into windows where they were saved.
Tab completing anything - You can complete lots of things with tab:
nicks, commands, command -options, file names, settings, text format
names, channels and server names. There's also an excellent /msg
completion that works transparently with multiple IRC networks.
Completing channel nicks is also pretty intelligent, it first goes
through the people who have talked to you recently, then the people who
have talked to anyone recently and only then it fallbacks to rest of
the nicks. You can also complete a set of words you've specified, for
example homepage
Excellent logging - You can log any way you want and as easily or hard as you want. With autologging Irssi logs everything to specified directory, one file per channel/nick. ircII style /WINDOW LOG ON is also supported. There's also the "hard way" of logging - /LOG command which lets you specify exactly what you wish to log and where. Log rotating is supported with all the different logging methods, you can specify how often you want it to rotate and what kind of time stamp to use.
Excellent ignoring - You can most probably ignore anything any way you want. Nick masks, words, regular expressions. You can add exceptions to ignores. You can ignore other people's replies in channels to nicks you have ignored. You can also specify that the specific ignores work only in specific channel(s).
Lastlog and scrollback handling - /LASTLOG command has some new
features: -new option checks only lines that came since you last did
/LASTLOG command, -away option checks new lines since you last went
away. Regular expression matches work also, of course. Going to some
wanted place at scrollback has always been hard with non-GUI clients. A
search command that jumps around in scrollback in GUI-style is still
missing from Irssi, but there's something that's almost as good as it.
/LASTLOG always shows timestamps when the line was printed, even if you
didn't have timestamps on. Now doing /SB GOTO
BUGS / SUGGESTIONS
See TODO file and http://bugs.irssi.org if it is already listed in there; if not open a bugreport on http://bugs.irssi.org or send a mail to staff@irssi.org
You can also contact the Irssi developers on #irssi @ EFnet, Freenode, IRCnet, Quakenet and Undernet.
The IRCnet channel is for development related questions and discussions.