[Linux] 使用 wget 測試 Remote Resource Availability @ Ubuntu 14.04

wget 有 --spider 模式，挺方便的 :P

$ wget --spider http://www.google.com/favicon.ico
Spider mode enabled. Check if remote file exists.
Resolving www.google.com (www.google.com)... 173.194.33.148, 173.194.33.144, 173.194.33.145, ...
Connecting to www.google.com (www.google.com)|173.194.33.148|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [image/x-icon]
Remote file exists.