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User1
Asked: 2010-07-16 14:02:04 +0800 CST

wmic hangs in Cygwin

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If I open Cygwin in rxvt, running wmic does not show the expected wmic:root\cli> prompt. If I execute C:\cygwin\bin\bash.exe from cmd.exe, running wmic inside bash.exe returns the expected prompt. Why?

I have the environment variable CYGWIN set to ntsec tty. I can echo "hello" with a response and everything else seems happy. It's just when I run wmic and a few other Windows applications that have a prompt, the prompt never appears.

wmi cygwin

4 Answers

  1. For wmic, try using echo '' | wmic <query here>, where <query here> is your desired query.

    For instance, to get a Dell machine's service tag over SSH: echo '' | wmic bios get serialnumber.

    Getting interactive mode to work seems fruitless to me, but this should expose most of wmic's functionality to you.

    Failed Attempts:

    One alternative solution I read was to use < /dev/null at the end instead of an echo '' | in the front, i.e.: wmic bios get serialnumber < /dev/null. I am not, however, having luck with this one. (from Nabble thread)

    Another alternative solution I read was to attempt to set tty in the CYGWIN environmental variable. That had no luck for me, either. (from a Larry Hall posting on the Cygwin mailing list, not linked due to spam prevention)

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  2. It's ye olde Cygwin pty vs native console app issue. Rxvt is based on a "pseudo terminal device" (pty), which Cygwin implements using Windows pipes. Non-Cygwin apps only see the Windows pipes though, which makes some of them think that they should enter non-interactive mode without a prompt. (More specifically, the isatty() function returns false when invoked on a pipe.)

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  3. Depending on the version of Cygwin you are using, you may have to leverage the < /dev/null. I believe I am using 1.7 and I no longer must use < /dev/null on most versions of Windows (the exception is Windows 2003 R2, you still must use < /dev/null.)

    Here is an example:

    wmic bios (works on almost all versions of Windows) wmic bios < /dev/null (works on all versions of Windows based on my testing)

    Hope this helps.

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  4. echo not required.

    Run in cygnin prompt:

    Administrator@darwin-test7-wi ~
$ wmic pagefileset where 'name="C:\\pagefile.sys"' delete
Deleting instance \\DARWIN-TEST7-WI\ROOT\CIMV2:Win32_PageFileSetting.Name="C:\\pagefile.sys"

Instance deletion successful.
=============================================

Administrator@darwin-test7-wi ~
$ wmic pagefileset create name="C:\\pagefile.sys"

Instance creation successful.
-----------------------------------------------------

Administrator@darwin-test7-wi ~
$ wmic pagefileset where 'name="C:\\pagefile.sys"' set InitialSize=512,MaximumSize=512

Updating property(s) of '\\DARWIN-TEST7-WI\ROOT\CIMV2:Win32_PageFileSetting.Name="C:\\pagefile.sys"'

Property(s) update successful.
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