PowerShell is a great framework for system administrators. It is fairly easy to learn and use, while allowing you to be extremely efficient.
#SAPonMS admins can use PowerShell to administrate their systems and improve their daily work flows, just like the developers in our team use it regularly in all kinds of situations. However, as much as I like PowerShell, I have got one issue with it:
The way it handles symbolic links .
It is quite common for admins to use symbolic links, but unfortunately the way they are shown in PowerShell is not what I would consider optimal. Let me show you what I mean before I will explain a possible workaround:
Imagine the following scenario: You have a certain file, let's call it "MyFile.txt" and it is located in
C:\MyDir\MyFile.txt
Then, you want to have a symbolic link to that file. For simplicity, let's put it in the same directory:
You can use the PowerShell Command
New-Item -Name C:\MyDir\MySymLinkFile.txt -ItemType SymbolicLink -Value C:\MyDir\MyFile.txt
to create such a link. You could of course also use the "good old" cmd prompt, which offers mklink.exe command.
Now, try to check the folder's content by using Get-Childitem:
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---l 7/30/2018 3:03 PM MySymLinkFile.txt
-a--- 7/30/2018 2:23 PM 12 MyFile.txt
You can immediately see what is bothering me: You don't recognize that you have a symbolic link. Of course, you can look at the item's length. However, that is no solution because the same issue holds true for symbolic links to folders. Creating a sub directory "SubDir" and a symlink to it, called "SymLinkSubDir", results in the following folder view:
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---l 7/30/2018 3:03 PM MySymLinkFile.txt
d---- 7/30/2018 3:14 PM SubDir
d---l 7/30/2018 3:14 PM SymLinkSubDir
-a--- 7/30/2018 2:23 PM 12 MyFile.txt
To be completely fair, it has to be stated that starting with PowerShell version 5, you can see that you are dealing with a symlink by looking at the "l" in the Mode property. This means, there is a way to tell the difference between the original folder and the symlink. But still, you cannot see the target that the link is pointing to. Pretty annoying, isn't it?
Assuming you have a more complicated setup and taking into account that you usually don't name your symlinks "symlink*", this has huge potential of confusion for other users and your future self.
So, how do we clean up this mess? First, please note that all of this assumes that we are using PowerShell version 5.
The general idea to fix our issue is to customize the format of the Get-ChildItem output and similar commands. PowerShell allows you to change the format view of almost anything. We want to get a clear visual hint if we have a link and we also want to know where it is linking to. The default format files are located in
C:\Windows\System32\WindowsPowerShell\v1.0
You can choose to place a custom format file there by creating a file called
C:\Windows\System32\WindowsPowerShell\v1.0\MyCustom.format.ps1xml
Open it and paste the following code in it:
<?xml version="1.0" encoding="utf-8" ?>
<!-- *******************************************************************
Taken from sample files used by the Windows PowerShell engine.
Modified formatting of directory output to include Symlinks and Hardlinks
******************************************************************** -->
<Configuration>
<SelectionSets>
<SelectionSet>
<Name>FileSystemTypes</Name>
<Types>
<TypeName>System.IO.DirectoryInfo</TypeName>
<TypeName>System.IO.FileInfo</TypeName>
</Types>
</SelectionSet>
</SelectionSets>
<!-- ################ VIEW DEFINITIONS ################ -->
<ViewDefinitions>
<View>
<Name>children</Name>
<ViewSelectedBy>
<SelectionSetName>FileSystemTypes</SelectionSetName>
</ViewSelectedBy>
<GroupBy>
<PropertyName>PSParentPath</PropertyName>
<CustomControlName>FileSystemTypes-GroupingFormat</CustomControlName>
</GroupBy>
<TableControl>
<TableHeaders>
<TableColumnHeader>
<Label>Mode</Label>
<Width>7</Width>
<Alignment>left</Alignment>
</TableColumnHeader>
<TableColumnHeader>
<Label>LastWriteTime</Label>
<Width>25</Width>
<Alignment>right</Alignment>
</TableColumnHeader>
<TableColumnHeader>
<Label>Length</Label>
<Width>14</Width>
<Alignment>right</Alignment>
</TableColumnHeader>
<TableColumnHeader>
<Label>Name</Label>
</TableColumnHeader>
</TableHeaders>
<TableRowEntries>
<TableRowEntry>
<Wrap/>
<TableColumnItems>
<TableColumnItem>
<PropertyName>Mode</PropertyName>
</TableColumnItem>
<TableColumnItem>
<ScriptBlock>
[String]::Format("{0,10} {1,8}", $_.LastWriteTime.ToString("d"), $_.LastWriteTime.ToString("t"))
</ScriptBlock>
</TableColumnItem>
<TableColumnItem>
<PropertyName>Length</PropertyName>
</TableColumnItem>
<TableColumnItem>
<ScriptBlock>
If(-not [string]::IsNullOrEmpty($_.Target))
{$_.Name + " --> "+ $_.Target + " (" + $_.LinkType + ")"}
else {$_.Name}
</ScriptBlock>
</TableColumnItem>
</TableColumnItems>
</TableRowEntry>
</TableRowEntries>
</TableControl>
</View>
</ViewDefinitions>
</Configuration>
Save it and go back to your PowerShell. You can load your customized format by calling
Update-FormatData -prependpath C:\Windows\System32\WindowsPowerShell\v1.0\MyCustom.format.ps1xml
If you don't want to type this again and again, you can put it in your PowerShell profile so that it loads automatically on startup. You can find your profile under
C:\Users\<user>\Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1
Afterwards, you can look at your folder again:
Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 7/30/2018 3:47 PM SubDir
d----l 7/30/2018 3:48 PM SymLinkSubDir --> C:\MyDir\SubDir\ (SymbolicLink)
-a---- 7/30/2018 3:47 PM 12 Myfile.txt
-a---l 7/30/2018 3:49 PM 0 MySymLinkFile.txt --> C:\MyDir\Myfile.txt (SymbolicLink)
Tadaaaa! That's it!
We get a clear view on our files and directories, while also getting the information where a link is pointing to. With these few steps, we can potentially save a lot of time the next time we are working on a system, which heavily uses symbolic links.
