Sorting out -GroupBy
Did you realize that Format-Table had a parameter -GroupBy? This tells Format-Table to generate a series of tables instead of a single table. The best way to get this in focus is to show an example.
For the purposes of this blog entry, I’m going to use the aliases GSV for Get-Service and FT for Format-Table. Also, I don’t want too much data for the examples so I’m going to leverage the fact that GSV supports wildcards and specify s[p-z]* which says give me all the services that start with “s” and whose second character is between “p” and “z” inclusive. There is nothing special about this, I just did some quick experimentation and that seemed to produce a reasonable dataset for this blog (and it allows me to show off wildcarding in GSV 🙂 ).
First let’s look at the output of GSV and then explore what additional information is available:
PS> gsv s[p-z]* |ft
Status Name DisplayName
—— —- ———–
Running Spooler Print Spooler
Stopped SQLBrowser SQL Server Browser
Stopped SQLWriter SQL Server VSS Writer
Running SRUserService IT Connection Manager
Running SSDPSRV SSDP Discovery
Running stisvc Windows Image Acquisition (WIA)
Stopped swprv Microsoft Software Shadow Copy Prov…
Running SysMain Superfetch
PS> gsv s[p-z]* |Get-Member -MemberType Property
TypeName: System.ServiceProcess.ServiceController
Name MemberType Definition
—- ———- ———-
CanPauseAndContinue Property System.Boolean CanPauseAndContinue {get;}
CanShutdown Property System.Boolean CanShutdown {get;}
CanStop Property System.Boolean CanStop {get;}
Container Property System.ComponentModel.IContainer Containe…
DependentServices Property System.ServiceProcess.ServiceController[]…
DisplayName Property System.String DisplayName {get;set;}
MachineName Property System.String MachineName {get;set;}
ServiceHandle Property System.Runtime.InteropServices.SafeHandle…
ServiceName Property System.String ServiceName {get;set;}
ServicesDependedOn Property System.ServiceProcess.ServiceController[]…
ServiceType Property System.ServiceProcess.ServiceType Service…
Site Property System.ComponentModel.ISite Site {get;set;}
Status Property System.ServiceProcess.ServiceControllerSt…
Notice that the ServiceController objects emitted by Get-Service (GSV) contain the field ServiceType . Let’s do this again but this time have Format-Table Group the services by ServiceType:
PS> gsv s[p-z]* |ft -GroupBy ServiceType
ServiceType: Win32OwnProcess, InteractiveProcess
Status Name DisplayName
—— —- ———–
Running Spooler Print Spooler
ServiceType: Win32OwnProcess
Status Name DisplayName
—— —- ———–
Stopped SQLBrowser SQL Server Browser
Stopped SQLWriter SQL Server VSS Writer
Running SRUserService IT Connection Manager
ServiceType: Win32ShareProcess
Status Name DisplayName
—— —- ———–
Running SSDPSRV SSDP Discovery
ServiceType: Win32OwnProcess
Status Name DisplayName
—— —- ———–
Running stisvc Windows Image Acquisition (WIA)
Stopped swprv Microsoft Software Shadow Copy Prov…
ServiceType: Win32ShareProcess
Status Name DisplayName
—— —- ———–
Running SysMain Superfetch
Now you get a series of tables.
But wait. Take a close look at those tables. Notice that you have 2 tables for both Win32ShareProcess and Win32OwnProcess. The reason for that is that is that Format-Table (ft) is STREAM-ORIENTED. By that I mean that it gets an object and processes it and then moves on to the next. It does that so that it doesn’t have to keep all the objects in memory. When it is done with the object, it is done with the object.
The only exception to this is when you specify -AutoSize . This tells Format-Table to collect all the objects and calculate the optimal column widths.
So the results we got are not quite what we wanted. The solution is to sort the object stream prior to sending it to Format-Table (Yes yes yes – let me preempt the question – given these semantics we could have chosen to do the sort in Format-Table. The reason we didn’t is that it would be wasteful if the stream was already properly sorted). So lets see what that looks like:
PS> gsv s[p-z]* |Sort ServiceType |ft -GroupBy ServiceType
ServiceType: Win32OwnProcess
Status Name DisplayName
—— —- ———–
Stopped SRUserService IT Connection Manager
Running stisvc Windows Image Acquisition (WIA)
Stopped swprv Microsoft Software Shadow Copy Prov…
Stopped SQLBrowser SQL Server Browser
Stopped SQLWriter SQL Server VSS Writer
ServiceType: Win32ShareProcess
Status Name DisplayName
—— —- ———–
Running SysMain Superfetch
Running SSDPSRV SSDP Discovery
ServiceType: Win32OwnProcess, InteractiveProcess
Status Name DisplayName
—— —- ———–
Running Spooler Print Spooler
Now that is much better but notice that within a table, things are not sorted by Status. No problem. Did you realize that sort can do a multi-key sort? After we sort by Status, we’ll figure out that we also want it sorted by Name as well so let’s do it all at once shall we?
PS> gsv s[p-z]* |Sort ServiceType,Status,Name |ft -GroupBy ServiceType
ServiceType: Win32OwnProcess
Status Name DisplayName
—— —- ———–
Stopped SQLBrowser SQL Server Browser
Stopped SQLWriter SQL Server VSS Writer
Stopped SRUserService IT Connection Manager
Stopped swprv Microsoft Software Shadow Copy Prov…
Running stisvc Windows Image Acquisition (WIA)
ServiceType: Win32ShareProcess
Status Name DisplayName
—— —- ———–
Running SSDPSRV SSDP Discovery
Running SysMain Superfetch
ServiceType: Win32OwnProcess, InteractiveProcess
Status Name DisplayName
—— —- ———–
Running Spooler Print Spooler
Cheers!
Jeffrey Snover [MSFT]
Windows PowerShell/MMC Architect
Visit the Windows PowerShell Team blog at: http://blogs.msdn.com/PowerShell
Visit the Windows PowerShell ScriptCenter at: http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx
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