Running openssl commands in PowerShell

Question

I'm executing the following command in PowerShell:

Invoke-Expression "openssl pkcs12 -in $certCN.pfx -nocerts -nodes -out $certCN.key -password pass:1111"

It works fine, however the output from openssl is causing ugly console errors:

openssl : MAC verified OK
At line:1 char:1
+ openssl pkcs12 -in www.mywebsite.com.pfx -nocerts -node ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (MAC verified OK:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

What's the best way to execute this OpenSSL command and have the output ignored or at least not interpreted as a command?

How is trying to get a powershell script to run without errors NOT a programming question again? — Dominic Brunetti
– Dominic Brunetti, Commented Nov 13, 2017 at 16:02

Bill_Stewart · Accepted Answer · 2017-11-08 22:52:42Z

13

You don't need Invoke-Expression (in fact, it's not recommended except in specific cases because it is susceptible to injection). Just run the command and quote the parameters where you need variable string expansion:

openssl pkcs12 -in "$certCN.pfx" -nocerts -nodes -out "$certCN.key" -password pass:1111

To ignore the output of the command, one common technique is to pipe to Out-Null.

edited Nov 8, 2017 at 22:52

answered Nov 8, 2017 at 22:46

Bill_Stewart

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6 Comments

Dominic Brunetti Over a year ago

Thank you - Not very familiar with powershell. I was planning on reading up tomorrow on invoke-expression vs. invoke-command. I'll give this a go.

Dominic Brunetti Over a year ago

Thanks. I've read up on them and see how they are pointless and risky. Also, FYI - I tried piping these commands to Out-Null and it didn't work. However appending the command with 2>&1 did. Thank you again.

Bill_Stewart Over a year ago

Out-Null doesn't redirect stderr, IIRC.

user3613932 Over a year ago

Where do you get openssl binaries from safely in case you don't want to build from source?

Heinzlmaen Over a year ago

@user3613932 If you have Git installed, you already have it at C:\Program Files\Git\usr\bin\openssl.exe

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