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May 2011 - Power Tips

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  • Find multiple matches

    When you want to find matches based on regular expressions, PowerShell will only support the -match operator which finds the first match. There does not seem to be a -matches operator that returns all matches. You can use Select-Object like so to find...

  • Finding multiple RegEx matches

    In a previous tip, you learned that Select-Object can find multiple matches. Here is a function called matches. You can submit a regular expressions pattern and all text piped into matches will be matched: $pattern = ' \b[A-Z0-9._%+-]+@[A-Z0-9.-]...

  • Making sure PowerShell scripts run in 32-bit

    If you are using code that can only run in a 32-bit environment (i.e. using old database drivers or COM objects), here is a solution that will re-launch the script in a 32-bit PowerShell when it is launched in a 64-bit environment: if ( $env:Processor_Architecture...

  • Use WMI to Create Hardware Inventory

    You can use Get-WMIObject to create a high-level hardware report. Instead of submitting a specific device class name, you should use a generic device class that applies to all hardware devices: PS > Get-WmiObject -Class CIM_LogicalDevice | Select-Object...

  • RegEx Magic

    The [RegEx] type has a method called Replace(), which can be used to replace text by using regular expressions. This line would replace the last octet of an IP address with a new fixed value: PS > [ Regex ] :: Replace ( ' 192.168.1.200 ' ,...

  • Getting Full Admin Privileges

    You may sometimes get "Access Denied" exceptions, even though you have Admin privileges and used an elevated shell. For example, this can hit you when you are trying to enable security-relevant PowerShell settings, such as enabling PowerShell...

  • Error handling for native commands

    When you need to handle errors created by native commands, you can use a wrapper function like Call. It will automatically discover when a native command writes to the error stream and return a warning: function Call { $command = $Args -join " "...

  • Running PowerShell on 64-bit systems

    On 64-bit systems, PowerShell will by default run in a 64-bit process. This can cause problems with snap-ins, some COM-objects (like ScriptControl) and database drivers that are designed to run in 32-bit processes. In this case, you can run them in the...

  • Test Internet connection

    Try this line if you would like to know whether a machine is currently connected to the Internet: [ Activator ] :: CreateInstance ([ Type ] :: GetTypeFromCLSID ([ Guid ] ' {DCB00C01-570F-4A9B-8D69-199FDBA5723B} ' )) . IsConnectedToInternet It...

  • Checking all event logs

    What if you would like to get a quick overview of all error events in any event log. Get-EventLog can only query one event log at a time. So, you can use -list to get the names of all event logs and then loop through them. The next line will get you the...

  • Secret history shortcut

    PowerShell will keep a history of the commands you entered and then you can list the history with Get-History, configuring the maximum length of that history with $MaxHistoryCount. This will tell PowerShell to keep the last 1,000 command lines in your...

  • Restart required

    Check out this line to determine when an installation required a system restart: Get-EventLog -InstanceId 1038 -LogName Application | ForEach-Object { $i = 1 | Select-Object Date , Product , Version , Company; ` $i . Date = $_ . TimeWritten ; $i . Product...

  • Find system restore points

    Windows Update and Software installations will frequently create system restore points. Run this to get a list of such events: Get-EventLog -LogName application -InstanceId 8194 | ForEach-Object { $i = 1 | Select-Object Event , Application; ` $i . Event...

  • Translate EventID to InstanceID

    Sometimes, you may need to have the event ID for a system event, though what you really need is the instance ID. For example, Get-EventLog will only support instance IDs, but no event IDs. Here is a function that can translate event IDs into instance...

  • Analyze automatic defragmentation

    Check out this line to visualize when your system defragmented your hard drives: get-eventlog -LogName Application -InstanceId 258 | ForEach-Object { $i = 1 | Select-Object Date , Type , Drive; ` $i . Date = $_ . TimeWritten ; $i . Type , ` $i . Drive...
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