construct/help/opers/who

WHO <#channel|nick|mask> [o][%format]

The WHO command displays information about a user, 
such as their GECOS information, their user@host, 
whether they are an IRC operator or not, etc.  A
sample WHO result from a command issued like 
"WHO pokey" may look something like this:

#lamers ~pokey ppp.example.net irc.example.com pokey H :0 Jim Jones

Clients often reorder the fields; the order in the
IRC protocol is described here.

The first field indicates the last channel the user
has joined.  The second is the username and the third
is the host.  The fourth field is the server the user
is on.  The fifth is the user's nickname.  The sixth
field describes status information about the user.
The possible combinations for this field are listed
below:

H       -       The user is not away.
G       -       The user is set away.
*       -       The user is an IRC operator.
@       -       The user is a channel op in the channel listed
                in the first field.
+       -       The user is voiced in the channel listed.

The final field displays the number of server hops and 
the user's GECOS information.

This command may be executed on a channel, such as
"WHO #lamers".  The output will consist of WHO 
listings for each user on the channel.  If you are
not on the channel, it must not have cmode +s set
and users with umode +i are not shown.

If the parameter is not a nickname or a channel, users
with matching nickname, username, host, server or
GECOS information are shown.  The wildcards * and ?
can be used.  Users with umode +i set that are not
on the same channel as you are not shown.

A second parameter of a lowercase letter o ensures
only IRC operators are displayed.

The second parameter may also contain a format
specification starting with a percent sign.
This causes the output to use numeric 354,
with the selected fields:

t       -       Query type. Outputs the given number in each reply.
c       -       Channel.
u       -       Username.
i       -       IP address.
h       -       Host.
s       -       Server.
n       -       Nickname.
f       -       Status.
d       -       Hop count.
l       -       Idle time or 0 for users on other servers.
a       -       Services account name or 0 if none.
r       -       GECOS information.

"WHO #lamers %tuhnf,42" would generate a brief listing
of channel members and include the number 42 in each
line.

See also: whois, userhost, cmode, umode