PowerShell 技能连载 - 重定向流

PowerShell 将输出信息写入六个不同的流,并且仅将输出流分配给变量:

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function Invoke-Test
{
"Regular Output"
Write-Host "You always see me!"
Write-Information "Info"
Write-Warning "Warning"
Write-Error "Error"
Write-Debug "Debug"
Write-Verbose "Verbose"
Write-Output "Output"
}

$result = Invoke-Test

其余所有流要么显示在控制台中,要么隐藏在控制台中,具体取决于其适当的首选项变量的设置:

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PS> Get-Variable -Name *preference -Exclude *confirm*,*whatif*,*progress*

Name Value
---- -----
DebugPreference SilentlyContinue
ErrorActionPreference Continue
InformationPreference SilentlyContinue
VerbosePreference SilentlyContinue
WarningPreference Continue

有时,可能还需要捕获其他流的输出并对其进行处理,而不是将其输出到控制台。为此,您可以将所有流重定向到输出流,并将总结果捕获到变量中:

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function Invoke-Test
{
"Regular Output"
Write-Host "You always see me!"
Write-Information "Info"
Write-Warning "Warning"
Write-Error "Error"
Write-Debug "Debug"
Write-Verbose "Verbose"
Write-Output "Output"
}


$all = Invoke-Test *>&1

现在,此变量包含所有流的组合输出。为了单独处理流,您可能需要按类型对内容进行分组:

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PS> $groups = $all | Group-Object -Property { $_.GetType().Name } -AsHashTable -AsString

PS> $groups

Name Value
---- -----
WarningRecord {Warning}
InformationRecord {You always see me!, Info}
ErrorRecord {Error}
String {Regular Output, Output}


PS> $groups.WarningRecord
WARNING: Warning

PS> $groups.InformationRecord
You always see me!
Info
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