Usage: LIST [<#channel mask>]
Shows all the public channels on the server. You can set a mask to limit the number of channels that are returned, in the example below we ask for any channels that start with the word support. Private or secret channels will not show up on the list.
/list #support*
The channel list may be very large, depending on the network. You can use the command LUSERS to see how many channels are on the network. The list command will take some time to display.