[27489] in Kerberos
Re: KfW 3.1: Re-directed stderr of kinit/klist displays dialog
daemon@ATHENA.MIT.EDU (petesea@bigfoot.com)
Thu Feb 22 15:57:43 2007
Date: Thu, 22 Feb 2007 12:56:10 -0800 (Pacific Standard Time)
From: petesea@bigfoot.com
In-reply-to: <6C19D6637F134D4A885DCE3AF06CEC0D@CDCHOME>
To: "Christopher D. Clausen" <cclausen@acm.org>
Message-id: <Pine.WNT.4.64.0702221152030.492@oberon.home.org>
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Cc: kerberos@mit.edu
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On Tue, 20 Feb 2007, Christopher D. Clausen wrote:
> Well, can't you check the exit error codes set by the program?
>
> C:\>kinit -kt test
> kinit(v5): Cannot resolve network address for KDC in requested realm
> while getting initial credentials
> C:\>echo %ERRORLEVEL%
> 1
Because that only tells you there was SOME kind of problem. It doesn't
tell you what the problem was.
I'm running kinit -kt as a background job ("Scheduled Task"). If it fails
I'd like to be able to log the reason it failed so I know how to fix it.
Just knowing that it failed doesn't really help much.
> Also, I can redirect the klist output just fine. What are you doing?
>
> C:\>klist 2>&1 1>%TEMP%\test.txt
> C:\>cat %TEMP%\test.txt
> Ticket cache: API:notguest@AD.UIUC.EDU
> Default principal: cclausen@AD.UIUC.EDU
> Valid starting Expires Service principal
> 02/20/07 18:14:49 02/21/07 04:14:49 krbtgt/AD.UIUC.EDU@AD.UIUC.EDU
stdOUT can be re-directed just fine, it's only stdERR that can't. Try
this:
C:\>klist -c foobar 2>klist.out
where "foobar" is a file that does NOT exist. This will generate an error
and since stderr is re-directed to a file, displays a Windows dialog.
Using the exact re-direct syntax you used, causes the behavior to be
different:
C:\>klist -c foobar 2>&1 1>klist.out
klist: No credentials cache found (ticket cache API:foobar)
The error output still doesn't go to the file, but it does go to the
terminal instead of a Windows dialog.
The reason this happens (and I'm going by the way UNIX redirection works),
is because "2>&1" says to redirect stderr to the same place as stdout, BUT
this happens when stdout is associated with the terminal, NOT the file.
The next part "1>klist.out" says to redirect stdout to a file... but
stderr is still re-directed to what stdout was BEFORE it was re-directed to
a file.
The correct (again at least in UNIX) way to redirect both stderr and
stdout to the same file is this:
command 1>somefile 2>&1
First you redirect stdout to a file and then you redirect stderr to the
same place stdout is going... which is now a file.
You can test this concept using any normal dos command that can generate
both stdout and stderr, eg:
(you type) C:\>ver 2>&1 1>test.txt
(you type) C:\>type test.txt
(displays) Microsoft Windows XP [Version 5.1.2600]
(you type) C:\>ver /z 2>&1 1>test.txt
(displays) The syntax of the command is incorrect.
(NOTE: test.txt is empty)
(you type) C:\>ver 1>test.out 2>&1
(you type) C:\>type test.txt
(displays) Microsoft Windows XP [Version 5.1.2600]
(you type) C:\>ver /z 1>test.out 2>&1
(you type) C:\>type test.txt
(displays) The syntax of the command is incorrect.
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