How to evaluate PowerShell script inputed from stdin

Question

I want to evaluate the content from StdIn in PowerShell, like this:

echo "echo 12;" | powershell -noprofile -noninteractive -command "$input | iex"

Output:

echo 12;

Unfortunately, $input is not a String, but a System.Management.Automation.Internal.ObjectReader, which make iex not working as expected... since this one is working correctly:

powershell -noprofile -noninteractive -command "$command = \"echo 12;\"; $command | iex"

Output:

Marcus · Accepted Answer · 2012-12-14 11:32:07Z

6

The following would work:

Use a scriptblock:

echo "echo 12;" | powershell -noprofile -noninteractive -command { $input | iex }

Or use single quotes to avoid the string interpolation:

 echo "echo 12;" | powershell -noprofile -noninteractive -command '$input | iex'

so the $input variable isn't expanded, and the string '$input' is passed to iex.

Both of these give me "12".

answered Dec 14, 2012 at 11:32

Marcus

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2 Comments

sandvige Over a year ago

This is working when you're running this from another PowerShell, but it's not working when using it from cmd.exe. Why?

Marcus Over a year ago

That's to do with the quotes around the "echo 12;". If you execute this in powershell echo "echo 12;" gives echo 12; without the quotes. In cmd.exe you'll see that it writes "echo 12;", which is then interpreted as a string by Powershell. To make it work in cmd.exe you can try: echo echo 12; | powershell -noprofile -noninteractive -command "$input | iex"

Martin Prikryl · Accepted Answer · 2021-04-21 05:28:05Z

4

Just use - as a source file "name":

echo "echo 12;" | powershell -noprofile -noninteractive -

answered Apr 21, 2021 at 5:28

Martin Prikryl

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