MissingEndParenthesisInMethodCall - checking if an environment variable is empty

Zundo Published at Dev

Zundo

I'm trying to check whether an environment variable is empty or unset in my PowerShell script. The script is running in a Docker container, and intended to pull new code if an environment variable is defined:

CMD if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { \
        Write-Host Git pull started; \
        PortableGit\bin\git.exe pull; \
    }; \

I get a bunch of errors:

web_1     | At line:1 char:110
web_1     | + ... ence = 'SilentlyContinue'; if (-not ([string]::IsNullOrEmpty(env:UPDA ...
web_1     | +                                                                  ~
web_1     | Missing ')' in method call.
web_1     | At line:1 char:110
web_1     | + ... ue'; if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { Wr ...
web_1     | +                                            ~~~~~~~~~~~~~~~~~~~~~~
web_1     | Unexpected token 'env:UPDATE_FROM_GITHUB' in expression or statement.
web_1     | At line:1 char:110
web_1     | + ... ence = 'SilentlyContinue'; if (-not ([string]::IsNullOrEmpty(env:UPDA ...
web_1     | +                                                                  ~
web_1     | Missing closing ')' in expression.
web_1     | At line:1 char:110
web_1     | + ... ue'; if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { Wr ...
web_1     | +                                            ~~~~~~~~~~~~~~~~~~~~~~
web_1     | Missing closing ')' after expression in 'if' statement.
web_1     | At line:1 char:132
web_1     | + ... e'; if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { Wri ...
web_1     | +                                                                 ~
web_1     | Unexpected token ')' in expression or statement.
web_1     | At line:1 char:133
web_1     | + ... '; if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { Writ ...
web_1     | +                                                                 ~
web_1     | Unexpected token ')' in expression or statement.
web_1     | At line:1 char:134
web_1     | + ... ; if (-not ([string]::IsNullOrEmpty(env:UPDATE_FROM_GITHUB))) { Write ...

I'm not sure how to begin here. The errors seem redundant, but there isn't a clear starting place. Could it have something to do with how Docker parses commands?

mklement0

PowerShell variables, including environment variables, must always be referred to with sigil $

Therefore, env:UPDATE_FROM_GITHUB must be $env:UPDATE_FROM_GITHUB

To simply test if an environment variable is defined / has a value, you don't strictly need -not [string]::IsNullOrEmpty(...); instead, you can take advantage of PowerShell's implicit Boolean conversion:

$null or the empty string is considered $False
and any nonempty string $True

To put it all together:

CMD if ($env:UPDATE_FROM_GITHUB) { \
        Write-Host Git pull started; \
        PortableGit\bin\git.exe pull; \
    }; \

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Please contact [email protected] to delete if infringement.

edited at2021-04-29

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MissingEndParenthesisInMethodCall - checking if an environment variable is empty

MissingEndParenthesisInMethodCall - checking if an environment variable is empty

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