Comments on: PowerShell script in a .bat file

By: Bruce Payette

Bruce Payette — Sun, 29 Jun 2008 00:27:05 +0000

One way to completely avoid the quoting problem is to use the -encoded parameter on powershell.exe. This takes a Base64 encoded string, decodes it and then executes it. For example, we’ll put some code in a script block (since it will be syntax checked) instead of a simple string:

PS (41) > $code = {
>> #iterate numbers 1 through 10
>> 1..10 | foreach-object {
>> # just output them
>> “Current output:”
>> $_
>> }
>>
>> }
>>

Now encode the command:

PS (42) > $encoded = [convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes($code))

The result of this looks like:

PS (43) > $encoded
MQAuAC4AMQAwACAAfAAgAGYAbwByAGUAYQBjAGgALQBvAGIAagBlAGMAdAAgAHsACgAjACAAagB1AHMAdAAgAG8AdQB0AHAAdQB0ACAAdABoAGUAbQAKACI
AQwB1AHIAcgBlAG4AdAAgAG8AdQB0AHAAdQB0ADoAIgAKACQAXwAKAH0ACgA=

Then run it:

(CXT: win7) (STA-ISS) (44) > powershell -encoded MQAuAC4AMQAwACAAfAAgAGYAbwByAGUAYQBjAGgALQBvAGIAagBlAGMAdAAgAHsACgAjACA
AagB1AHMAdAAgAG8AdQB0AHAAdQB0ACAAdABoAGUAbQAKACIAQwB1AHIAcgBlAG4AdAAgAG8AdQB0AHAAdQB0ADoAIgAKACQAXwAKAH0ACgA=

BTW – PowerShell has built-in support for this so when you call powershell from powershell with a scriptblock, the script block is automatically encoded and passed to the child process:

(CXT: win7) (STA-ISS) (46) > powershell { “Hi there. Today is ” + (get-date).DayOfWeek }
Hi there. Today is Saturday

-bruce
——————–
Principal Developer, Windows PowerShell Team
Microsoft

By: Andy

Andy — Sat, 28 Jun 2008 00:47:03 +0000

powershell.exe -command “1..10 | foreach-object { ‘Current output:’; $_; }”

By: Stuart

Stuart — Fri, 27 Jun 2008 11:59:30 +0000

As far as I can see, the double quotes will get the command interpreter confused, so you will have to escape them – as in

powershell.exe -command “1..10 | foreach-object { \”Current ou
tput:\”; $_; }”

If you don’t escape them you get the message:

The term ‘Current’ is not recognized as a cmdlet, function, operable program, or script file. Verify the term and try again.
At line:1 char:33
+ 1..10 | foreach-object { Current <<<< output:; $_; }

You also missed off the closing double quote, but that didn’t seem to make a difference.

Thanks for the post though, it could be useful for short scripts.