ping multiple hosts

foreach host $hosts {
	set pipe [open |[list ping -c 1 $host]]
	chan configure $pipe -blocking 0
	chan event $pipe readable [list receive $pipe $host]
}

proc receive {fd host} {
	if {[eof $fd]} {
		chan configure $fd -blocking 1
		if {[catch {close $fd} err info]} {
			puts [dict get $info -errorCode]
		}
	} elseif {[gets $fd line] >= 0} {
		puts "$host: $line"
	}
}