See the perldocs for kill. If you send the signal 0, it doesn't really kill the process, just lets you know if it was able to send the signal -- which turns into if the process id was alive to recieve it. In fact, kill is perhaps a misnomer, as it implies that it always sends a SIGKILL to the process; perhaps signal might haver been a better name for the construct.</code>

Update: It's funny how sometimes a good textual description of the problem translates so well to pseudocode and thence to code. If you read the above description, it's a fairly good summation of how one might go about coding the problem, nearly line-by-line. Of course, one could be perverse and dop it in about five statements using a hideous map / grep / join combination, but to each their own..

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'