Question 81569 in Docker Question posted in
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[Environment]::SetEnvironmentVariable Docker on Windows

In my dockerfile I have the line

RUN [Environment]::SetEnvironmentVariable("Path", $env:Path + ";C:oracleinstantclient_19_10", "Machine")

I get this returned, even though when I run the above command in PowerShell everything "just works"

At line:1 char:114
+ ...  = 'SilentlyContinue'; [Environment]::SetEnvironmentVariable(Path, $e ...
+                                                                  ~
Missing ')' in method call.
At line:1 char:114
+ ... SilentlyContinue'; [Environment]::SetEnvironmentVariable(Path, $env:P ...
+                                                              ~~~~
Unexpected token 'Path' in expression or statement.
At line:1 char:118
+ ... ilentlyContinue'; [Environment]::SetEnvironmentVariable(Path, $env:Pa ...
+                                                                 ~
Missing argument in parameter list.
At line:1 char:162
+ ... entVariable(Path, $env:Path + ;C:oracleinstantclient_19_10, Machine ...
+                                                                 ~
Missing argument in parameter list.
At line:1 char:171
+ ... ntVariable(Path, $env:Path + ;C:oracleinstantclient_19_10, Machine)
+                                                                         ~
Unexpected token ')' in expression or statement.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordEx 
   ception
    + FullyQualifiedErrorId : MissingEndParenthesisInMethodCall
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2

Answers


  1. Chosen as BEST ANSWER
    0

    Note: This answer isn't quite correct, check out the accepted answer https://stackoverflow.com/a/74142485/3684640 for the correct reason for why this is happening

    This is an unfortunate clash with Docker's two forms of run commands referenced here https://docs.docker.com/engine/reference/builder/#run.

    There's shell form:

    RUN (shell form, the command is run in a shell, which by default is /bin/sh -c on Linux or cmd /S /C on Windows)

    And there's exec form

    RUN ["executable", "param1", "param2"] (exec form)

    In Powershell with the command you're trying to use "[Environment]" is at the beginning which makes Docker think we are in exec form.

    A potential fix that works is

    RUN ["powershell.exe", "[Environment]::SetEnvironmentVariable("Path", $env:Path + ";C:\oracle\instantclient_19_10", "Machine")"]

    Which works by using exec form instead of shell form, since this is in json syntax we have to escape all the necessary characters as well.


  2. 0

    The error message implies two things:

    • PowerShell is configured as your default shell in your dockerfile (by default it is cmd.exe)

    • However, the " characters were stripped from your PowerShell command, which broke it.

    Therefore, escape the " character as ":

    RUN [Environment]::SetEnvironmentVariable("Path", $env:Path + ";C:oracleinstantclient_19_10", "Machine")

    Alternatively, you can simply use '-quoting in this case:

    RUN [Environment]::SetEnvironmentVariable('Path', $env:Path + ';C:oracleinstantclient_19_10', 'Machine')

    As for why escaping " as " is needed:

    • Presumably, what follows RUN is copied as-is to the powershell.exe -Command command line that is used behind the scenes.

    • During PowerShell’s command-line parsing, unescaped " characters are removed before the resulting code is interpreted as PowerShell code. Thus, " characters that must be retained as part of the PowerShell code must be "-escaped.

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