irssi hide join part messages

/ignore #channel_name JOINS PARTS QUITS
/save

忽略所有系統訊息：

/ignore #channel CRAP NOTICES SNOTES CTCPS JOINS PARTS QUITS KICKS MODES WALLOPS NICKS DCC DCCMSGS CLIENTNOTICES CLIENTCRAP CLIENTERRORS HILIGHTS

套用至多個 channel：

/ignore -channels #roomA,#roomB,#etc * JOINS PARTS QUITS NICKS

References :
Hide join part messages - XKCD Wiki
LoCoDays/JoiningIn - Ubuntu Wiki
Irssi hacks | fossline