a function to find the fastest free DNS server

timeDNS () { { for x in "${local_DNS}" "208.67.222.222" "208.67.220.220" "198.153.192.1" "198.153.194.1" "156.154.70.1" "156.154.71.1" "8.8.8.8" "8.8.4.4"; do ({ echo -n "$x "; dig @"$x" "$*"|grep Query ; }|sponge &) done ; } | sort -n -k5 ; }
Evoke from the command like as: timeDNS commandlinefu.com . This isn't too terribly practical, but it is a good code example of using subshells to run the queries in parallel and the use of an "anonymous function" (a/k/a "inline group") to group i/o. . I'm assuming you have already defined your local DNS cache as ${local_DNS}, (here, it's 192.168.0.1). . You do need to install `moreutils` to get `sponge`. . If you're willing to wait, a slower version w/o sponge, (and w/o sorting), is this: . DNS () { for x in "192.168.0.1" "208.67.222.222" "208.67.220.220" "198.153.192.1" "198.153.194.1" "156.154.70.1" "156.154.71.1" "8.8.8.8" "8.8.4.4"; do (echo -n "$x "; dig @"$x" "$*"|grep Query) ; done ; }
Sample Output
$ timeDNS commandlinefu.com
192.168.0.1 ;; Query time: 2 msec
208.67.222.222 ;; Query time: 13 msec
198.153.192.1 ;; Query time: 17 msec
208.67.220.220 ;; Query time: 17 msec
156.154.71.1 ;; Query time: 18 msec
8.8.8.8 ;; Query time: 20 msec
156.154.70.1 ;; Query time: 22 msec
8.8.4.4 ;; Query time: 22 msec
198.153.194.1 ;; Query time: 27 msec

1
2011-08-18 01:11:53

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What Others Think

This is odd. Today is the 22nd, and I posted it on the 18th, yet it's still not visible. WTF?
unixmonkey365 · 377 weeks and 3 days ago

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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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