{"id":11110,"date":"2016-02-10T06:00:04","date_gmt":"2016-02-10T14:00:04","guid":{"rendered":"https:\/\/www.sapien.com\/blog\/?p=11110"},"modified":"2016-02-06T15:57:55","modified_gmt":"2016-02-06T23:57:55","slug":"use-group-object-to-detect-command-name-conflicts","status":"publish","type":"post","link":"https:\/\/dev.sapien.com\/blog\/2016\/02\/10\/use-group-object-to-detect-command-name-conflicts\/","title":{"rendered":"Using Group-Object to Detect Command Name Conflicts"},"content":{"rendered":"

The Group-Object<\/a> cmdlet, one of the original provider cmdlets<\/a>,\u00a0is as old as Windows PowerShell. It was introduced in version 1.0 and hasn’t changed at all since then. But, it is one of my favorites. (You can tell\u00a0when I love a cmdlet by the number of examples. Group-Object has 9!) In fact, when you use it frequently, you begin to see groups as\u00a0a\u00a0path to many solutions.<\/p>\n

Group-Object<\/strong> groups objects by the values of a property that you choose. So, it’s a quick way to find the property values that appear in a data set. Which domain controllers are used by users in this department? What command types are exported by this module? It’s also a great way to detect duplicate and unique values. (Really, try a few of the 9 examples.)<\/p>\n

In this post, I’ll be using an old cmdlet to help with a new problem — detecting multiple commands with the same name on the same machine.\u00a0 Because\u00a0providers and\u00a0repositories\u00a0offer more\u00a0modules, we can install module versions side-by-side on 5.0,\u00a0and we can install them in a blink without much consideration, name collisions are more likely than ever.<\/p>\n

\n

Detect commands with the same name<\/h1>\n

To detect commands with the same names in your installed modules, use the Get-Command <\/a>cmdlet to get all commands in all installed modules. Then, use the Group-Object<\/strong> cmdlet to group commands by the value of their Name<\/strong> property. The result is a collection of groups where each group contains\u00a0commands with the same name.<\/p>\n

Some groups have just one member. But, each group that Group-Object<\/strong>\u00a0returns has a Count<\/strong> property that indicates the number of\u00a0objects in the group. That makes it easy to use the Where-Object<\/strong> cmdlet to find groups that have more than one member.<\/p>\n

$groups = Get-Command | Group-Object -Property Name | Where Count -gt 1<\/pre>\n
Let’s look at one of the multi-member groups. This is one for the Describe command in the Pester module. I use and study Pester pretty obsessively, so I have multiple versions of the Pester module on my test machine.<\/p>\n
PS C:\\> $groups | where Name -eq 'Describe'\r\n\r\nCount Name                      Group\r\n----- ----                      -----\r\n    6 Describe                  {Describe, Describe, Describe, Describe...}<\/pre>\n
This group has\u00a06 members, that is,\u00a06 Describe commands.<\/p>\n
Each group that Group-Object<\/strong> returns also has a Group<\/strong> property that contains the members of the group. In this case, the Group<\/strong> property of the Describe group contains\u00a0the Describe\u00a0commands.<\/p>\n
PS C:\\> ($groups | where Name -eq 'Describe').Group\r\n\r\nCommandType     Name             Version    Source\r\n-----------     ----             -------    ------\r\nFunction        Describe         3.3.13     Pester\r\nFunction        Describe         3.3.11     Pester\r\nFunction        Describe         3.3.9      Pester\r\nFunction        Describe         3.3.10     Pester\r\nFunction        Describe         3.3.8      Pester\r\nFunction        Describe         3.3.5      Pester\r\n<\/pre>\n
The Describe\u00a0duplicates\u00a0represent the same command in different versions of the same module. But, we also find commands with the same name in different modules, such as this Set-Clipboard<\/strong> command.<\/p>\n
PS C:\\> ($groups | where Name -eq 'Set-Clipboard').Group\r\n\r\nCommandType     Name                 Version    Source\r\n-----------     ----                 -------    ------\r\nCmdlet          Set-Clipboard        3.1.0.0    Microsoft.PowerShell.Management\r\nCmdlet          Set-Clipboard        3.2.1.0    Pscx<\/pre>\n
Detect commands with same name in different modules<\/h1>\n
To get commands with the same names in modules with different names, use Group-Object to create groups based on\u00a0the Source<\/strong> (module name) property value of each command and look for groups with more than one unique Source<\/strong> value.<\/p>\n
To count the number of sources\u00a0that the second Group-Object<\/strong> command returns, I use the Length<\/strong> property that PowerShell adds to all objects, because the\u00a0Count<\/strong> property is the number of objects in the group.<\/p>\n
Get-Command | Group-Object -Property Name | where { $_.Count -GT 1 -and ($_.Group | Group-Object -Property Source).Length -gt 1 }<\/pre>\n
To display the groups, I use the Format-Table<\/a> cmdlet with a calculated property for the Source <\/strong>value.<\/p>\n
$diftModules = Get-Command | Group-Object -Property Name | where { $_.Count -GT 1 -and ($_.Group | Group-Object -Property Source).Length -gt 1 }\r\n\r\n$diftModules | Format-Table -Property Name, @{Label = 'Module'; Expression = { $_.Group.Source } }<\/pre>\n
 <\/p>\n
Which command runs?<\/h1>\n
Now, that we can find commands with the same name, I’d like to know which command runs by default when I invoke that command without a\u00a0qualifying\u00a0module or version. The answer is not some new-fangled cmdlet. It’s good old Get-Command<\/a>.<\/p>\n
When the value of the Name<\/strong> parameter includes wildcard characters (*), Get-Command<\/strong> gets all commands with the specified name. But, when the value of the Name<\/strong> parameter has no wildcards, Get-Command<\/strong> gets the command that runs by default; the one that takes precedence.<\/p>\n
For example, using a wildcard character (*) in Name, you can see\u00a0the two\u00a0Set-Clipboard<\/strong> commands that Group-Object detected.<\/p>\n
PS C:\\> Get-Command Set-Clipboard*\r\n\r\nCommandType\u00a0\u00a0\u00a0\u00a0 Name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Version\u00a0\u00a0\u00a0 Source\r\n-----------\u00a0\u00a0\u00a0\u00a0 ----\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0-------\u00a0\u00a0\u00a0 ------\r\nCmdlet\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Set-Clipboard\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a03.1.0.0\u00a0\u00a0\u00a0 Microsoft.PowerShell.Management\r\nCmdlet\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Set-Clipboard\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a03.2.1.0\u00a0\u00a0\u00a0 Pscx<\/pre>\n
To find the one that runs by default,\u00a0run Get-Command<\/strong> with no wildcard characters. It’s the newest version in the user-specific module directory.<\/p>\n
PS C:\\> Get-Command Set-Clipboard\r\n\r\nCommandType\u00a0\u00a0\u00a0\u00a0 Name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Version\u00a0\u00a0\u00a0 Source\r\n-----------\u00a0\u00a0\u00a0\u00a0 ----\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0-------\u00a0\u00a0\u00a0 ------\r\nCmdlet\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Set-Clipboard\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a03.1.0.0\u00a0\u00a0\u00a0 Microsoft.PowerShell.Management<\/pre>\n
This is very helpful. But, what do you do to make sure that you’re running the command that you want to run? Stay tuned for a series of posts on different strategies to avoid mistakes.<\/p>\n
 <\/p>\n
June Blender is a technology evangelist at SAPIEN Technologies, Inc. and a Windows PowerShell MVP. You can reach her at <\/em>juneb@sapien.com<\/em><\/a>\u00a0and follow her on Twitter at <\/em>@juneb_get_help<\/em><\/a>.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
The Group-Object cmdlet, one of the original provider cmdlets,\u00a0is as old as Windows PowerShell. It was introduced in version 1.0 and hasn’t changed at all since then. But, it is one of my favorites. (You can tell\u00a0when I love a cmdlet by the number of examples. Group-Object has 9!) In fact, when you use it […]<\/p>\n","protected":false},"author":31,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[932,1034,2,283,941,703,25],"tags":[934,28,961,1016],"class_list":["post-11110","post","type-post","status-publish","format-standard","hentry","category-beginners","category-best-practices","category-general","category-howto","category-powershell-5-0","category-powershell-studio","category-windows-powershell","tag-juneb","tag-powershell","tag-powershell-5-0","tag-powershell-studio"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/11110","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/users\/31"}],"replies":[{"embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/comments?post=11110"}],"version-history":[{"count":15,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/11110\/revisions"}],"predecessor-version":[{"id":11129,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/11110\/revisions\/11129"}],"wp:attachment":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/media?parent=11110"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/categories?post=11110"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/tags?post=11110"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}