WHO

The WHO command is used to query information about users matching a given mask or channel.

User Information Query
Usage: WHO [<channel> | <mask> [<option>]]
<channel> (Optional) The channel to retrieve user information from.
<mask> (Optional) The mask to match against user nicknames, hostnames, servernames, or realnames.
<option> (Optional) An option to filter the results.

Options:
o Server Operators.
w Users receiving wallops messages.
g Away users.
h Present users.

This command retrieves information about users matching the specified mask or within a given channel. If no mask or channel is given, all users are returned. Options can be used to filter the results.

(See section 4.5.1 of RFC 1459, 3.6.1 of RFC 2812)