Hidden configuration variables in PowerShell

Tobias & Aleksandar's tip #13:

The two very well-known PowerShell experts have teamed up to share their best and most helpful PowerShell tips.

We will be publishing their scripts over the course of Scriptember in 13 blog posts. Don't miss their insights! Be sure to follow all Scriptember events, listed in our calendar here. 

Overview of all 13 articles published during Scriptember: 

• #1 using enums (Part 1)
• #2 using enums (Part 2)
• #3 utilizing external config data (Part 1)
• #4 utilizing external config data (Part 2)
• #5 utilizing external config data (Part 3)
• #6 utilizing external config data (Part 4)
• #7 always use advanced functions
• #8 adding help links to functions
• #9 harvest command history
• #10 filter empty properties
• #11 URL encoding
• #12 hiding confirmations
• #13 hidden configuration variables 
  
  

Hidden configuration variables

There are two important configuration variables in PowerShell that have great impact on formatting, yet aren’t always seen.

$ofs (output field separator) contains one space by default. It is the character(s) that PowerShell uses when automatically turning arrays into strings:

PS C:\> $lottery = 1..49 | Get-Random -Count 7



PS C:\> "Lottery Numbers: $lottery"

Lottery Numbers: 22 2 48 44 23 13 4



PS C:\> $ofs = ', '



PS C:\> "Lottery Numbers: $lottery"

Lottery Numbers: 22, 2, 48, 44, 23, 13, 4



PS C:\> $ofs = ','



PS C:\> "Lottery Numbers: $lottery"

Lottery Numbers: 22,2,48,44,23,13,4

$FormatEnumerationLimit defaults to 4. This is the number of array elements that PowerShell includes in any string conversion preview. Here is an example:

Get-Service | 

   Where-Object { $_.DependentServices.Count -gt 1 } |

   Select-Object -Property Name, Dep* 

You get a list with services that have at least 2 dependent services. When you look closely at the results, you see that a maximum of 4 dependent services are visible. If a service has more, the list is cut off, and "…" is shown:

NlaSvc               {NcdAutoSetup, AppVClient, netprofm}                       

nsi                  {WlanSvc, icssvc, Wcmsvc, upnphost...}                     

p2pimsvc             {PNRPAutoReg, p2psvc, PNRPsvc}                             

PNRPsvc              {PNRPAutoReg, p2psvc}                                      

ProfSvc              {XblGameSave, TokenBroker, UserManager, shpamsvc...}       

SamSs                {MSDTC, KAPSService, LanmanServer, KtmRm}   

When you set $FormatEnumerationLimit to any other number, you can control this limit. Setting it to -1 disables any limit and always shows all elements:

• PS C:\> $FormatEnumerationLimit = -1 
  
  

Now all entries are visible:

NlaSvc               {NcdAutoSetup, AppVClient, netprofm}                                                           

nsi                  {WlanSvc, icssvc, Wcmsvc, upnphost, SSDPSRV, NcdAutoSetup, AppVClient, netprofm, NlaSvc, KND...

p2pimsvc             {PNRPAutoReg, p2psvc, PNRPsvc}                                                                 

PNRPsvc              {PNRPAutoReg, p2psvc}                                                                          

ProfSvc              {XblGameSave, TokenBroker, UserManager, shpamsvc, NaturalAuthentication, Appinfo}              

SamSs                {MSDTC, KAPSService, LanmanServer, KtmRm}   

Except, with "nsi" in this example, there is still a "…" and cut-off. This time, however, it was triggered by the console space constraints. To overcome these as well, you’d need to add Format-Table:

Get-Service | 

   Where-Object { $_.DependentServices.Count -gt 1 } |

   Select-Object -Property Name, Dep* |

   Format-Table -Wrap -AutoSize 

Now the output finally lists all output without cutting off anything:

NlaSvc               {NcdAutoSetup, AppVClient, netprofm}                                                           

nsi                  {WlanSvc, icssvc, Wcmsvc, upnphost, SSDPSRV, NcdAutoSetup, AppVClient, netprofm, NlaSvc,       

                     KNDBWM, KAPSService, Netman, NcaSvc, SessionEnv, Netlogon, LanmanWorkstation, Killer Network   

                     Service, jhi_service, IpxlatCfgSvc, iphlpsvc, XboxNetApiSvc, IKEEXT, hns, Dnscache,            

                     WinHttpAutoProxySvc, Dhcp}                                                                     

p2pimsvc             {PNRPAutoReg, p2psvc, PNRPsvc}                                                                 

PNRPsvc              {PNRPAutoReg, p2psvc}                                                                          

ProfSvc              {XblGameSave, TokenBroker, UserManager, shpamsvc, NaturalAuthentication, Appinfo}              

SamSs                {MSDTC, KAPSService, LanmanServer, KtmRm}   

Related links 

• Scriptember calendar
• Try out ScriptRunner here
• ScriptRunner: Book a demo with our product experts