Two Ruby equivalents to Powershell commands...

[Nicholas Calvert]

Hi,

I’m in the process of transferring a bunch of script from powershell to
ruby to aid interoperability with an existing application and I’m
looking for two ruby equivalents to powershell commands:

PSBASE is a view which returns the raw view of an object.
getText returns the text between the current location and the specified
location in the buffer.

I use these a lot with WMI code in powershell, an example:

$Var1 = path to WMI class or object
$Var1.psbase.gettext(1) > wmi.xml

This would give me pure XML of a WMI object.

Any help greatly appreciated.

 

[Gordon Thiesfeld]

Hi,

I'm in the process of transferring a bunch of script from powershell to
ruby to aid interoperability with an existing application and I'm
looking for two ruby equivalents to powershell commands:

PSBASE is a view which returns the raw view of an object.
getText returns the text between the current location and the specified
location in the buffer.

I use these a lot with WMI code in powershell, an example:

$Var1 = path to WMI class or object
$Var1.psbase.gettext(1) > wmi.xml

This would give me pure XML of a WMI object.

I'm not sure that you need PSBASE outside of powershell, I could be
wrong, though. GetText in OLE land is called GetText_.

Win32OLE example:
?> wmi = WIN32OLE.connect("winmgmts://")
?> processes = wmi.ExecQuery("select * from win32_process")
?>
?> for process in processes do
?> p process.gettext_(1)"<INSTANCE CLASSNAME=\"Win32_Process\"><PROPERTY NAME=\"__PATH\"
CLASSORIGIN=\"_
...

Ruby-WMI example:
=> "<INSTANCE CLASSNAME="Win32_Process"><PROPERTY NAME="__PATH" CLASSORIGIN="
...

Hope that helps.

Gordon

 

[Nicholas Calvert]

Cheers Gordon, you are a life saver. Whilst im on the same subject, i am
also having trouble creating a new GUID. With Powershell i can do:

$NEWGUID = [GUID]::NewGUID().ToString()

Do you think its possible to do this with Ruby and ruby-wmi?

Many thanks,

Nick

 

[Jano Svitok]

Cheers Gordon, you are a life saver. Whilst im on the same subject, i am
also having trouble creating a new GUID. With Powershell i can do:

$NEWGUID = [GUID]::NewGUID().ToString()

Do you think its possible to do this with Ruby and ruby-wmi?

This is how I create GUIDs (requires win32utils gem, might not be
tested - I'm reinstalling ruby right now):

require 'windows/com'
require 'windows/unicode'

class String
# Return the portion of the string up to the first NULL character. This
# was added for both speed and convenience.
def nstrip
self[ /^[^\0]*/ ]
end
end

class Guid

BUFFER_SIZE = 100

attr_reader :data

def initialize(data = nil)
@data = data
create if data.nil?
end

def create
@data = 0.chr * 16
raise 'GUID Error' unless CoCreateGuid(@data)
end

def to_s
ret = 0.chr * BUFFER_SIZE
i = StringFromGUID2(@data, ret, BUFFER_SIZE)
wide_to_multi(ret[0..i*2]).nstrip
end

private

include Windows::COM
include Windows::Unicode

end

if File.expand_path(__FILE__) == File.expand_path($0)
puts Guid.new.to_s
end

 

[Nicholas Calvert]

Thanks Jano. If you have a minute, do you think you could run through
that code and explain what its doing? I am new to Ruby and a large
portion of that went over my head

Nick

 

[Jano Svitok]

Thanks Jano. If you have a minute, do you think you could run through
that code and explain what its doing? I am new to Ruby and a large
portion of that went over my head

1. You'll find documentation for CoCreateGuid here:
http://msdn.microsoft.com/en-us/library/ms688568(VS.85).aspx
and for StringFromGUID2 here:
http://msdn.microsoft.com/en-us/library/ms683893(VS.85).aspx
(these are C functions from ole32.dll)

2. I call them using WIN32API, conveniently wrapped by windows-pr gem
from win32utils project.

### these are from windows-pr gem
require 'windows/com'
require 'windows/unicode'

### helper function to strip everything past the first NULL character.
Copied from some file in win32utils
class String
# Return the portion of the string up to the first NULL character. This
# was added for both speed and convenience.
def nstrip
self[ /^[^\0]*/ ]
end
end

class Guid

BUFFER_SIZE = 100

attr_reader :data

### two ways of using this class - 1. either provide GUID in binary
form Guid.new(data) or create a new one (Guid.new)
def initialize(data = nil) ### nil is default value for data parameter
@data = data
create if data.nil? ### if there's no data, call create
end

### create new guid
def create
@data = 0.chr * 16 ### make empty buffer for the binary GUID "\0\0\0\0...\0"
raise 'GUID Error' unless CoCreateGuid(@data) ### call the API. the
call will place the created GUID in @data.
end

### convert binary guid to string representation
def to_s
ret = 0.chr * BUFFER_SIZE ### temporary buffer to place the string form
i = StringFromGUID2(@data, ret, BUFFER_SIZE) ### call the API
### API returns zero-terminated wide string. this is the conversion to
ordinary ruby string.
### wide_to_multi is from windows/unicode
wide_to_multi(ret[0..i*2]).nstrip
end

private

### this code includes COM and Unicode modules into this class, so
that we can use them.
include Windows::COM
include Windows::Unicode

end

### this line is kind of idiom/guard
### it allows to specify code to be run when the file is run directly.
This code will not run
### if this file is required or included in another file. (script vs. library)
if File.expand_path(__FILE__) == File.expand_path($0)
puts Guid.new.to_s
end