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As part of a task that I am working on for a customer, I need to make some modifications to the enterprise logon script. Windows command-line is definitely not my area of expertise, but I am doing OK with most it. However, I have one problem that I cannot figure out how to do.

Basically, I need to get the IP address of the machines default gateway into an environment variable (for later use in the script). I know that it exists in the output of both ipconfig and of tracert, and I know how to find the exact line in their output that I need, but I cannot figure out how to get beyond that.

For example, the following command produces output like this:

>ipconfig|Find "Default Gateway"|Findstr/N "."|Findstr/B "1:"

 1:   Default Gateway . . . . . . . . . : 199.99.9.1

But now I need to somehow extract only the IP address out of this text line and then assign it to an environment variable. So, how can I do that from a Windows command-line? (Windows XP and higher).

RBarryYoung
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1 Answers1

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for /f is your friend. 

for /f "usebackq tokens=1,2,3 delims=:" %A in (`ipconfig ^| Find "Default Gateway" ^| Findstr/N "." ^| Findstr/B "1:"`) do @if not defined MYVAR set MYVAR=%~C

...might do the trick.

Edit: changed the code block to read the third value not the second, and needed to escape the pipes.

You could also shorten to:

for /f "usebackq tokens=1,2,3 delims=:" %A in (`ipconfig ^| Find "Default Gateway" ^| Findstr/N "."`) do @if not defined MYVAR set MYVAR=%~C

...as, technically, the second findstr (where you limit to the first result) is actually handled by the if not defined

jimbobmcgee
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  • OK, that's completely new to me. I'll check it out ... – RBarryYoung Jan 14 '13 at 22:35
  • Wow, that works great. But it is coming back with some leading spaces. Is there any convenient way to trim them off? – RBarryYoung Jan 14 '13 at 22:55
  • Ironically, another `for /f` with "delims= " would do it - for /f "usebackq delims= " %A in (`echo %MYVAR%`) do @set MYVAR=%A – jimbobmcgee Jan 14 '13 at 22:57
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    Or, possibly, `SET MYVAR=%MYVAR: =%` (in theory, replace spaces in MYVAR with nothing -- YMMV) – jimbobmcgee Jan 14 '13 at 22:58
  • Yep, I just now figured out that string substitution (Set A=%A: =%) would work. Thanks! – RBarryYoung Jan 14 '13 at 23:10
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    Ever notice that hardly anyone uses For/if and environment variables anymore ? Tons of expert advice across the web from people insisting you type out hard paths "c:\program files" and just change it for your system instead of just %programfiles% or others. Jim, are you and old hand or just learned from old wizards ? I detect experience in your Fu –  Jan 14 '13 at 23:02
  • Old enough but, really, everything I learned about batch I learned from http://robvanderwoude.com (and maybe http://ss64.com) – jimbobmcgee Jan 14 '13 at 23:03
  • +1 - epic batch is epic. I never could get the syntax of `for` right - it once cost me a job interview for a dream job. – Mark Henderson Jan 15 '13 at 02:37