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powershell/PSAvoidAssignmentToAutomaticVariable is a PSScriptAnalyzer diagnostic emitted by tally for PowerShell snippets embedded in Dockerfiles.
PropertyValue
SeverityWarning
CategoryPSScriptAnalyzer
Auto-fixNo

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Description

PowerShell has built-in variables known as automatic variables. Many of them are read-only and PowerShell throws an error when trying to assign a value on those. Other automatic variables should only be assigned in certain special cases to achieve a certain effect as a special technique. To understand more about automatic variables, see Get-Help about_Automatic_Variables.

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How

Use variable names in functions or their parameters that do not conflict with automatic variables.

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Examples

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Problematic code

The variable $Error is an automatic variable that exists in the global scope and should therefore never be used as a variable or parameter name. 
function foo($Error){ }

function Get-CustomErrorMessage($ErrorMessage){ $Error = "Error occurred: $ErrorMessage" }

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Correct code

function Get-CustomErrorMessage($ErrorMessage){ $FinalErrorMessage = "Error occurred: $ErrorMessage" }

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Source

This rule documentation is adapted from Microsoft’s PSScriptAnalyzer documentation for AvoidAssignmentToAutomaticVariable, licensed under CC BY 4.0.