Ruby

* [, timeout]]]) -> array or nil

* Calls select(2) system call.

* It monitors given arrays of <code>IO</code> objects, waits one or more

* of <code>IO</code> objects ready for reading, are ready for writing,

* and have pending exceptions respectably, and returns an array that

* contains arrays of those IO objects. It will return <code>nil</code>

* if optional <i>timeout</i> value is given and no <code>IO</code> object

* is ready in <i>timeout</i> seconds.

*

* === Parameters

* read_array:: an array of <code>IO</code> objects that wait until ready for read

* write_array:: an array of <code>IO</code> objects that wait until ready for write

* error_array:: an array of <code>IO</code> objects that wait for exceptions

* timeout:: a numeric value in second

*

* === Example

*

* rp, wp = IO.pipe

* mesg = "ping "

* 100.times {

* rs, ws, = IO.select([rp], [wp])

* if r = rs[0]

* ret = r.read(5)

* print ret

* case ret

* when /ping/

* mesg = "pong\n"

* when /pong/

* mesg = "ping "

* end

* end

* if w = ws[0]

* w.write(mesg)

* end

* }

*

* <em>produces:</em>

*

* ping pong

* ping pong

* ping pong

* (snipped)

* ping