dig returns 0 regardless of result of query

[Lars Noodén]

/usr/bin/dig returns 0 regardless of whether the query was successful or not. It should return 0 instead if the query failed.

[Lars Noodén (larsnooden)]

Sorry it should return 1 instead if the query failed.

[Stéphane Bortzmeyer (stephane+launchpad-o)]

What do you mean "failed"? NXDOMAIN? SERVFAIL? Timeout? They are very different things. I would strongly object to returning 1 when the answer is NXDOMAIN (the query succeeded).

[Lars Noodén (larsnooden)]

I would expect dig to respond in this manner:

dig +short www.google.com && echo SUCCESS || echo FAILURE

[Dave Walker (davewalker)]

I'm not convinced the exit code can be handled how you want it. A lookup that returns NXDOMAIN was a successful lookup, so IMO shouldn't return an exit code of non-zero.

is this not a valid work around for what you want?
dig www.google.com | grep NOERROR 1>/dev/null && echo SUCCESS || echo FAILURE

[Lars Noodén (larsnooden)]

It's a work around but I'd still expect dig to return a non-zero number sometimes.

[Stéphane Bortzmeyer (stephane+launchpad-o)]

You never specified what you want. "Sometimes"??? Is that a specification? For instance, NXDOMAIN is *not* an error.

May be you actually want something like:

 ADDRS=$(dig +short www.google.com); if [ -z "$ADDRS" ]; then echo FAILURE; else echo SUCCESS; fi

For another example of testing dig results, see the script in http://www.bortzmeyer.org/files/try-get-zone.sh

[Launchpad Janitor (janitor)]

[Expired for bind9 (Ubuntu) because there has been no activity for 60 days.]

[Jeff Silverman (jeffsilverm)]

It turns out that the host command will do what you want.

jeffs@jeffs-desktop:~$ host www.g00gle.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:

Host www.g00gle.com not found: 2(SERVFAIL)
jeffs@jeffs-desktop:~$ echo $?
1 <===================================================
jeffs@jeffs-desktop:~$ host www.google.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:

www.google.com has address 216.58.216.164
www.google.com has IPv6 address 2607:f8b0:400a:805::1013
jeffs@jeffs-desktop:~$ echo $?
0
jeffs@jeffs-desktop:~$ host www.google.com 10.82.34.123
;; connection timed out; no servers could be reached
jeffs@jeffs-desktop:~$ echo $?
1
jeffs@jeffs-desktop:~$

[Alexey Kopytko (sanmai)]

You can use grep to detect that dig returns a non-empty string

    dig +short www.google.not-com | grep -v -e '^$' > /dev/null && echo SUCCESS || echo FAILURE

prints FAILURE

    dig +short www.google.com | grep -v -e '^$' > /dev/null && echo SUCCESS || echo FAILURE

prints SUCCESS