Change graph output encoding in pipe (powershell)

Question

I'm using terraform on windows, and would like to visualize the graphs using Graphviz. However, there is a difference between the encoding that is being output by Terraform vs what Graphviz expects. Ideally, I want to do the following:

terraform graph -draw-cycles |  dot -Tsvg > output.svg

That doesn't work, because the output that is being given by terraform is in the wrong encoding. The following sequence works, but uses an intermediate file:

terraform graph -draw-cycles > output.tmp 
Get-Content .\output.tmp | Set-Content -Encoding Ascii output2.tmp
dot -Tsvg output2.tmp > output.svg
rm output.tmp
rm output2.tmp

However, I would like to do this without intermediate files using piping. A statement such as

terraform graph -draw-cycles | Set-Content -Encoding Ascii -PassThru | dot -Tsvg > output.svg

doesn't work. The output from the terraform graph statement is text, and apparantly the Set-Content commandlet needs additional information (Path?):

Set-Content : The input object cannot be bound because it did not contain the information required to bind all mandatory parameters:  Path
At line:1 char:32
+ ... rm graph -draw-cycles | Set-Content -Encoding Ascii -PassThru | dot - ...
+                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (digraph {:PSObject) [Set-Content], ParameterBindingException
    + FullyQualifiedErrorId : InputObjectMissingMandatory,Microsoft.PowerShell.Commands.SetContentCommand

Any suggestions?

Set-Content needs a -Path or -LiteralPath to a file it can write content to — Theo
– Theo, Commented Nov 12, 2021 at 11:05
Have a look at [Console]::OutputEncoding. See this answer. — zett42
– zett42, Commented Nov 12, 2021 at 11:31
@Theo so I guess I can't use Set-Content then for my purpose.... — Yves V.
– Yves V., Commented Nov 12, 2021 at 12:24

Yves V. · Accepted Answer · 2021-11-12 12:28:11Z

1

After reading the article referred to by zett42, I saw a reference to CMD pipe different form Powershell pipe? in the comments.

The easiest solution for my specific case is simply executing the call with cmd:

cmd /c "terraform graph -draw-cycles | dot -Tsvg > output.svg"

Using the Invoke-WithEncoding would also work, but is a little more involved.

answered Nov 12, 2021 at 12:28

Yves V.

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