ping and its cross-references

ping

ping [<string>]
Replies with hopefully-useful information, including:
* Current time, number of IRC and system users, and load averages.
* Most recent traffic on a relevant channel (if sent privately, any
  channel we're both on, otherwise the channel in question.)  Only
  actual message traffic counts, and !-commands don't count either.
* The specified string, if any.
I can tell you this automatically if you like - see `help marktime'.
If you have undelivered messages sent with tell by or to you, I'll
let you know about those too (privately, if you ping on channel).

marktime

set marktime off        Only an explicit `ping' command sends info.
set marktime once       Send ping info shortly after I first see you.
set marktime <interval> Also send info regularly (min. interval 5m).

tell

tell <nick> <message ...>
 Leaves a message for someone, which will be delivered according to
 their `set tellme'.  I will tell you about your undelivered tells
 whenever I see you arriving, or when you say `ping'.  See also
 `help untell' and `help delmsg'.