PowerShell中的百分号"%"和问号"?"

研究一个问题, 发现一篇White Paper上写的PowerShell上有如下的语句:

$farmName = Get-spfarm |%{ $_.Name }

笔者PowerShell比较弱, 看不懂百分号的意思. 于是询问了专家Tracy Yu. 得到如下的答复:

这里的百分号是个PowerShell中的Alias, 意思是ForEach-Object.

如图:

不推荐写PowerShell的时候使用这些Alias, 不方便其他人看懂.

另外, Alias是可以通过命令New-Alias新定义, 和使用Set-Alias另外修改的.

默认所有Alias的完整列表如下:

CommandType     Name                            Definition
-----------     ----                            ----------
Alias           %                               ForEach-Object
Alias           ?                               Where-Object
Alias           ac                              Add-Content
Alias           asnp                            Add-PSSnapIn
Alias           cat                             Get-Content
Alias           cd                              Set-Location
Alias           chdir                           Set-Location
Alias           clc                             Clear-Content
Alias           clear                           Clear-Host
Alias           clhy                            Clear-History
Alias           cli                             Clear-Item
Alias           clp                             Clear-ItemProperty
Alias           cls                             Clear-Host
Alias           clv                             Clear-Variable
Alias           compare                         Compare-Object
Alias           copy                            Copy-Item
Alias           cp                              Copy-Item
Alias           cpi                             Copy-Item
Alias           cpp                             Copy-ItemProperty
Alias           cvpa                            Convert-Path
Alias           dbp                             Disable-PSBreakpoint
Alias           del                             Remove-Item
Alias           diff                            Compare-Object
Alias           dir                             Get-ChildItem
Alias           ebp                             Enable-PSBreakpoint
Alias           echo                            Write-Output
Alias           epal                            Export-Alias
Alias           epcsv                           Export-Csv
Alias           epsn                            Export-PSSession
Alias           erase                           Remove-Item
Alias           etsn                            Enter-PSSession
Alias           exsn                            Exit-PSSession
Alias           fc                              Format-Custom
Alias           fl                              Format-List
Alias           foreach                         ForEach-Object
Alias           ft                              Format-Table
Alias           fw                              Format-Wide
Alias           gal                             Get-Alias
Alias           gbp                             Get-PSBreakpoint
Alias           gc                              Get-Content
Alias           gci                             Get-ChildItem
Alias           gcm                             Get-Command
Alias           gcs                             Get-PSCallStack
Alias           gdr                             Get-PSDrive
Alias           ghy                             Get-History
Alias           gi                              Get-Item
Alias           gjb                             Get-Job
Alias           gl                              Get-Location
Alias           gm                              Get-Member
Alias           gmo                             Get-Module
Alias           gp                              Get-ItemProperty
Alias           gps                             Get-Process
Alias           group                           Group-Object
Alias           gsn                             Get-PSSession
Alias           gsnp                            Get-PSSnapIn
Alias           gsv                             Get-Service
Alias           gu                              Get-Unique
Alias           gv                              Get-Variable
Alias           gwmi                            Get-WmiObject
Alias           h                               Get-History
Alias           history                         Get-History
Alias           icm                             Invoke-Command
Alias           iex                             Invoke-Expression
Alias           ihy                             Invoke-History
Alias           ii                              Invoke-Item
Alias           ipal                            Import-Alias
Alias           ipcsv                           Import-Csv
Alias           ipmo                            Import-Module
Alias           ipsn                            Import-PSSession
Alias           ise                             powershell_ise.exe
Alias           iwmi                            Invoke-WMIMethod
Alias           kill                            Stop-Process
Alias           lp                              Out-Printer
Alias           ls                              Get-ChildItem
Alias           man                             help
Alias           md                              mkdir
Alias           measure                         Measure-Object
Alias           mi                              Move-Item
Alias           mount                           New-PSDrive
Alias           move                            Move-Item
Alias           mp                              Move-ItemProperty
Alias           mv                              Move-Item
Alias           nal                             New-Alias
Alias           ndr                             New-PSDrive
Alias           ni                              New-Item
Alias           nmo                             New-Module
Alias           nsn                             New-PSSession
Alias           nv                              New-Variable
Alias           ogv                             Out-GridView
Alias           oh                              Out-Host
Alias           popd                            Pop-Location
Alias           ps                              Get-Process
Alias           pushd                           Push-Location
Alias           pwd                             Get-Location
Alias           r                               Invoke-History
Alias           rbp                             Remove-PSBreakpoint
Alias           rcjb                            Receive-Job
Alias           rd                              Remove-Item
Alias           rdr                             Remove-PSDrive
Alias           ren                             Rename-Item
Alias           ri                              Remove-Item
Alias           rjb                             Remove-Job
Alias           rm                              Remove-Item
Alias           rmdir                           Remove-Item
Alias           rmo                             Remove-Module
Alias           rni                             Rename-Item
Alias           rnp                             Rename-ItemProperty
Alias           rp                              Remove-ItemProperty
Alias           rsn                             Remove-PSSession
Alias           rsnp                            Remove-PSSnapin
Alias           rv                              Remove-Variable
Alias           rvpa                            Resolve-Path
Alias           rwmi                            Remove-WMIObject
Alias           sajb                            Start-Job
Alias           sal                             Set-Alias
Alias           saps                            Start-Process
Alias           sasv                            Start-Service
Alias           sbp                             Set-PSBreakpoint
Alias           sc                              Set-Content
Alias           select                          Select-Object
Alias           set                             Set-Variable
Alias           si                              Set-Item
Alias           sl                              Set-Location
Alias           sleep                           Start-Sleep
Alias           sort                            Sort-Object
Alias           sp                              Set-ItemProperty
Alias           spjb                            Stop-Job
Alias           spps                            Stop-Process
Alias           spsv                            Stop-Service
Alias           start                           Start-Process
Alias           sv                              Set-Variable
Alias           swmi                            Set-WMIInstance
Alias           tee                             Tee-Object
Alias           type                            Get-Content
Alias           where                           Where-Object
Alias           wjb                             Wait-Job
Alias           write                           Write-Output