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Guy's Top 10 Free Tools

1) FreePing
2) Network Monitor
3) Xobni
4) PuTTY (UNIX)
5) WMI Monitor
6) BgInfo
7) Net-SNMP
8) Engineer's Toolset
9) DNS Stuff
10) WinDiff

PowerShell Scripting  -Recurse

Introduction to PowerShell Scripting -Recurse

When you want a PowerShell command to search sub-directories -recurse is a life saver.  In other contexts this concept is called iteration, or sub-directory recursion.  The cmdlet which benefits most from the -recurse parameter is Get-Childitem.

Topics for PowerShell -Recurse Parameter

• Example 1 Get-ChildItem -recurse
• Example 2 Searching The Registry with -recurse
• Example 3 More Complex Example
• Troubleshooting PowerShell -recurse
• Scope of the -recurse Parameter
• Problems with -recurse, and how to overcome them

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Example 1 Get-ChildItem -recurse

Our mission is to list all the Windows files under the Program Files folder.  It was the positioning of -recurse that gave me my biggest headache.  My tactical error was to try and introduce -recurse into a long statement.  What I should have done was take my own advice and build up gradually like this:-

Stage 1 Problem: The script lists files only in the top level directory.

Note 1: Get-Childitem is the equivalent of dir.  In fact PowerShell creates an alias called dir, thus this old command still works on the command line.

Stage 2 Solution: -Recurse drills down and finds lots more files.

Note 2:  The key to -recurse is the position, it has to be directly after the directory.  In this example I have explicitly used -path to define the location.

Example 2 Searching The Registry with -recurse

In addition to the file system, Get-ChildItem can work with the registry

Example 3 More Complex Example

I only include this example to explain how difficult it can be to decide where to place -recurse.  When you study that long middle line you can see how it's possible to group the output and select a custom format-Table (ft).

Note 4:  You can improve this script by adding -ErrorAction to skip the error message on protected or in use executables.

See how to add -ErrorAction SilentlyContinue if you get problems.

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Troubleshooting PowerShell -recurse

The problem with the -recurse parameter is that it only works where the object has leaf items, for example:
C: \Windows\  -recurse.  My point is, I was caught out by trying C: \Windows\*.dll -recurse.

To see my point try these two examples:

Note 5:  The answer was only about 17.  This script lists .exe files only in the actual Windows folder.  -recurse is useless here.

Note 6:  Expected answer over 2,000.  -recurse does its job.  'Where-Object' plays its role in filtering.  Alternatively, you could employ the -include parameter.

Scope of the -recurse Parameter

While -recurse works nicely for the above Get-Childitem, I emphasise CHILDitem.  I could neither get it to work with Get-Item, nor could I see -recurse amongst the parameters for plain Get-Item.

Research: Find PowerShell -recurse Cmdlets

Incidentally, Get-Childitem | Get-Member does not, repeat not, list -recurse.  This is because -recurse is a parameter, or what I call a switch.  Get-Member lists methods and properties, but not parameters, to see more about -recurse you need:

Problems with -recurse, and How to Overcome Them

Case Study

The mission is to list all files containing the word 'Microsoft' in the Windows folder or its sub-folders.  For this we use the select-string pattern matching command.

The problem is that this script does not work.  All that happens is that we get an error: Cannot find path... Path does not exist.

The Solution: Add the -include parameter

Note 7:  When we add -include *.txt the cmdlet works as initially planned.  Actually, you could swap the famous *.* for *.txt, thus : -include *.*

Note 8: -include only works when you also append the -recurse parameter.

Note 9: -include applies to the filename and extension.  Where I made a mistake was thinking that -include would apply to the path.

Simplification

There is no reason why you cannot simplify the above example by removing at least two of the variables, especially on a production script.  The only reason that I employed $Path and $StringText is that when I am creating a script I like to isolate and control each step of the way.

Summary of PowerShell -Recurse

-Recurse is a classic switch, which instructs PowerShell commands such as Get-ChildItem to repeat in sub directories.  Once you remember that -recurse comes directly after the directory, then it will serve you well in scripts that need to drill down to find information.

See more PowerShell examples

• PowerShell Home   • Syntax  • Get-Credential   • Foreach loops   • Variables   • -whatIf  • -ErrorAction

• PowerShell Functions   • [System.Math]   • Windows 7 PowerShell 2.0   • PowerShell 2.0 New features

Please write in if you have a better example script.  Also please report any factual mistakes, grammatical errors or broken links, I will be happy to  correct the fault.

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