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POUnexpected behavior with Get-Job when only one job running
 

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  1. POUnexpected behavior with Get-Job when only one job running
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    <p>I'm new to Powershell and I'm having an issue with the Get-Job command. In my script, I'm testing out multi-threading and am doing something like:</p> <pre><code>$Program = { "Thread " + $args[0]; Start-Sleep 5; } Start-Job $Program -ArgumentList @($i) | Out-Null </code></pre> <p>The Start-Job call is actually in a loop in which I'm creating multiple jobs. Below this, I have:</p> <pre><code>Get-Job "Jobs Running: " + $(Get-Job -State Running).count </code></pre> <p>If there are multiple jobs running, I will get output like:</p> <pre><code>Id Name State HasMoreData Location Command -- ---- ----- ----------- -------- ------- 2201 Job2201 Running True localhost ... 2199 Job2199 Running True localhost ... 2197 Job2197 Running True localhost ... 2195 Job2195 Running True localhost ... 2193 Job2193 Completed True localhost ... 2191 Job2191 Completed True localhost ... 2189 Job2189 Completed True localhost ... 2187 Job2187 Completed True localhost ... Jobs Running: 4 </code></pre> <p>But if there is only one job running, it seems that <code>$(Get-Job -State Running).count</code> isn't returning anything:</p> <pre><code>Id Name State HasMoreData Location Command -- ---- ----- ----------- -------- ------- 2207 Job2207 Running True localhost ... Jobs Running: </code></pre> <p>As you can see, there is one job running, but <code>$(Get-Job -State Running).count</code> doesn't return anything. Any idea what's happening here? To me, it looks like that if there are multiple jobs, <code>$(Get-Job -State Running)</code> returns a collection of jobs which has the .count property, whereas if there is only one job, it returns just that job, and doesn't have the .count property. If this is the case (or if I'm doing something wrong), what command should I be using to get my expected result of <code>$(Get-Job -State Running).count == 1</code>?</p>
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    1. USDiscoInfiltrator
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    1. COYou're seeing a bit PSH "helpfulness" (helpful often, but sometimes not): If an expression (including a pipeline) returns a single object you get that object, if there are zero or more than one objects then an array is returned. Therefore if only one job exists `Get-Job` returns that job object which does not have a `Count` (or `Length`) property. Fix for when you always want an array is not force an array by using `@(…)` (eg. `$jobs = @(get-job)`).
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      1. USRichard
    2. COSo if there is only one job, `$jobs` is an array containing that job. If there are multiple jobs, Since `Get-Job` would already return an array, wouldn't I expect `$jobs` to be an array containing an array of jobs? Perhaps there is more PSH "helpfulness" at work here?
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      1. USDiscoInfiltrator
    3. CONo: if there is *one* job then `$jobs` will be that job object; otherwise it will be an array of jobs. Wrap in `@(...)` to always get an array.
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