This is the original version of the classic FAQ dating back to the early 1990s, and is kept here for historical reasons only. For up to date information on this subject, please see the revised bot FAQ.
A BOT is akin to a roBOT, hence the name. A bot is quite simply a computer program that hooks into IRC and does things automatically. Most bot programs are written in the C language that run as a background task and hook into IRC via Telnet connections. Others are written in the ircII script language and require some form of client to run and connect into IRC.
Most bots are used to "guard" a channel and keep it open when no one is present. They protect against net-split hacks, various forms of flooding and op the regulars that visit the channel. Some enforce bans and kick certain people (usually 'trouble makers') off the channel. Other exotic bots such as Robey Pointers Eggdrop bot use direct client to client connections to make a secondary relay chat network that is in itself independent to IRC.
Not all bots are written to be helpful, some such as HackBot use the bugs in IRC to takeover channels and nick-collide certain people. There are numerous uses for a BOT, some are useful, most are not.
Well, generally bots are quiet except for when someone makes them do something or something occurs that make the bot react. An example of this is when someone floods a channel and then is promptly kicked out of the channel and possibly banned as well. Two other things to look for are the words "bot" or "srv" in the nickname. Look in the username field, the ( )s at the end of a /whois <nick>. An example of a bot could be:
#junk JunkyBot H@ email@example.com(/msg JunkyBot Hello) #idiots IdiotSrv H@ firstname.lastname@example.org(/msg IdiotSrv Help)
Before one even gets the bot program one has several things to take into consideration. First off one must find a suitable host that the bot can be run from. Many people attempt to run a bot on their student account; most of the time the bot gets killed by other local students or gets killed by the local admin (IRCop). This results in an unstable bot that for all practical purposes is useless and could quite possibly cause a conflict between the user and his admin.
Second, one must find a suitable server that will allow a bot to connect. This requires reading the Message Of The Day on the server one wishes to run the bot on. If one ignores the "NO BOTS" warning posted on the server one may quickly find himself (or his entire host) k-lined (banned) from that server. Many servers do not allow bots, in fact most of them do not. The third consideration that one must make is the lag time. If the bot is lagged several seconds behind because of slow connections it's ability to react to possible floods and net-split hacks is severely handicapped.
Next one must select (or write) a bot program. There are several types of bots available. Some common ones are: Eggdrop, ComBot, and VladBot to name a few. Most bot programs come in packages that are fairly easy to install if one has a basic understanding of the language it is written in. Many are set up simply by editing the make file to the type of operating system the bot will be run on and customizing various other files to the owners taste.
Next the bot must be compiled by running the make file. Most of the time the bot will compile fine; but differences in systems might require the owner makes changes directly in the code to get it up and running. This requires some understanding of the language and the logic the program uses. If the compiling goes well; the next step is run the bot.
If everything runs well the bot will pop onto IRC in the channel you specify. At this point the owner needs to fine tune the bot. If you are placing the bot in a channel where another bot is, one must take care that the bots don't "fight" by having conflicting mode changes. An example of this is when someone is actively being opped by one bot while another is actively deopping him. When this occurs expect screen fulls of mode changes. Another example is when 2 or more bots are "locking" channel modes. If they conflict; again, there will be screens full of mode changes. This can result flooding the channel, might even cause the channel to be "out of synch". When this occurs not much can be done except to empty the channel of its occupants and start over.
Notice: The new client codes will not allow certain flags to be used for the bot to connect. Do not be surprised if you get your bot all set up and cannot connect it to IRC.
It is HIGHLY advisable one knows the language the bot is written in because of the possibility of backdoors. Such backdoors could possibly allow someone to enter the account itself and take it over without the owner even knowing it occurred until one day he finds his password is changed and can't get into his account. "Don't load ANYTHING until you know what it does." ALWAYS look before you load. This applies not only to bot programs, but to script files as well. Just a friendly warning; otherwise you may regret it later down the road.
Not as simple as you thought 'eh?
You must understand that MOST bots are useless. To keep a channel open with a bot in place is a serious waste of IRC resources. EFnet is extremely crowded, a bot takes up enough room for about 8 people, room which is meant for people, not programs. Yes, there ARE useful bots, these are few and far between. The game bots located on various game channels are fun, permission has been given by the administrators of the servers they are on to have them there. There are service bots as well, such as help_uk, AI-, and helper, to name a few. Eliza is one of the original bots on EFnet, located on #Eliza, the "grand dame"...a fun but perfectly useless type of bot. It is highly recommended that you do not start a bot for the sole purpose of retaining ops on a channel and to keep a channel open. If your channel is popular enough there is no need for this.