How to count objects in PowerShell

Question

As I m reading in the PowerShell user guide  one of the core PowerShell concepts is that commands accept and return objects instead of text  So for example  running get-alias returns me a number of System Management Automation AliasInfo objects    PS Z    get-alias  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       Now  how do I get the count of these objects

User · Answer

output  Count does not always produce correct results  I used the   output   Measure  Count method   I found this with VMware Get-VmQuestion cmdlet    output   Get-VmQuestion -VM vm1    output  Count   The answer it gave is one  whereas   output   produced no output  the correct answer was 0 as produced with the Measure method    This only seemed to be the case with 0 and 1  Anything above 1 was correct with limited testing

User · Answer

As short as  jumbo s answer is  -  you can do it even more tersely  This just returns the Count property of the array returned by the antecedent sub-expression     Get-Alias  Count   A couple points to note    You can put an arbitrarily complex expression in place of Get-Alias  for example     Get-Process          ProcessName -eq  svchost     Count  The initial at-sign     is necessary for a robust solution  As long as the answer is two or greater you will get an equivalent answer with or without the    but when the answer is zero or one you will get no output unless you have the   sign   It forces the Count property to exist by forcing the output to be an array     2012 01 30 Update  The above is true for PowerShell V2  One of the new features of PowerShell V3 is that you do have a Count property even for singletons  so the at-sign becomes unimportant for this scenario

User · Answer

This will get you count   get-alias   measure   You can work with the result as with object    m   get-alias   measure  m Count   And if you would like to have aliases in some variable also  you can use Tee-Object    m   get-alias   tee -Variable aliases   measure  m Count  aliases   Some more info on Measure-Object cmdlet is on Technet    Do not confuse it with Measure-Command cmdlet which is for time measuring   again on Technet

User · Answer

in my exchange the cmd-let you presented did not work  the answer was null  so I had to make a little correction and worked fine for me    get-transportservice   get-messagetrackinglog -Resultsize unlimited -Start  quot MM DD AAAA HH MM quot  -End  quot MM DD AAAA HH MM quot  -recipients  quot user domain com quot    where     Event ID -eq  quot DELIVER quot    count

User · Answer

Just use parenthesis and  count     This applies to Powershell v3   get-alias  count

[powershell] How to count objects in PowerShell?

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