> ## Documentation Index
> Fetch the complete documentation index at: https://tally.wharflab.com/llms.txt
> Use this file to discover all available pages before exploring further.

# powershell/PSAvoidExclaimOperator

> Avoid exclaim operator

`powershell/PSAvoidExclaimOperator` is a PSScriptAnalyzer diagnostic emitted by tally for PowerShell snippets embedded in Dockerfiles.

| Property | Value            |
| -------- | ---------------- |
| Severity | Warning          |
| Category | PSScriptAnalyzer |
| Auto-fix | No               |

## Description

Avoid using the negation operator (`!`). Use `-not` for improved readability.

<Note>
  Upstream PSScriptAnalyzer does not enable this rule by default. Configure `rules.powershell.PSAvoidExclaimOperator.Enable = true` to forward the
  upstream setting to PSScriptAnalyzer.
</Note>

## How to Fix

Replace the `!` negation operator with the PowerShell `-not` operator.

## Examples

### Problematic code

```powershell theme={null}
$MyVar = !$true
```

### Correct code

```powershell theme={null}
$MyVar = -not $true
```

## Configuration

Upstream PSScriptAnalyzer supports the following rule setting. tally forwards matching `rules.powershell.PSAvoidExclaimOperator` options to
PSScriptAnalyzer.

```powershell theme={null}
Rules = @{
    PSAvoidExclaimOperator  = @{
        Enable = $true
    }
}
```

### Parameters

* `Enable`: **bool** (Default value is `$false`)

  Enable or disable the rule during ScriptAnalyzer invocation.

## Source

This rule documentation is adapted from Microsoft's PSScriptAnalyzer documentation for
[AvoidExclaimOperator](https://github.com/MicrosoftDocs/PowerShell-Docs-Modules/blob/main/reference/docs-conceptual/PSScriptAnalyzer/Rules/AvoidExclaimOperator.md),
licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).