Windows PowerShell is an extensible, objected-oriented scripting language with full support for variables, looping, and pipelining. Use the Get-Help cmdlet to learn more about other commands. Use Get-Alias to find aliases for commands. PowerShell also has commands for reading from or writing to a file, starting a debugger, and checking event logs.
PowerShell is an extensible, objected-oriented scripting language with full support for variables, looping, and pipelining. Microsoft has made Power- Shell the scripting framework for almost all of its new products. For instance, PowerShell is integrated into the management consoles for both Microsoft Exchange Server 2007 and the upcoming System Center Virtual Machine Manager 2007. However, while PowerShell represents a revolutionary step in Windows scripting, it’s also a very different technology from its predecessors, the Windows command shell and VBScript. PowerShell has a new set of commands (called cmdlets) and command syntax that you need to learn. To help you get up to speed, here are 10 essential PowerShell cmdlets.
Get-Help—The Get-Help cmdlet helps you learn how to use PowerShell. Get-Help not only explains the syntax of commands, but it also provides examples of how to use them. The following example shows how to use Get-Help to learn about the PowerShell Help system itself:
cd—You can use the good ole’ cd (Change Directory) command to navigate between folders. Under the covers, cd is an alias for the Set- Location cmdlet. What sets this command apart from the old Windows shell cd command is its ability to navigate the registry. To use cd to go into the HKEY_LOCAL_MACHINE\SOFTWARE subkey, you would enter
Get-Alias—PowerShell has more than a hundred different aliases. Plus, you can create custom aliases with the New-Alias cmdlet. Use the Get-Alias cmdlet (or its alias, gal) to list all the Power-Shell aliases along with their native counterparts:
gal | select name, definition
Get-Command—You use the Get-Command cmdlet to retrieve a list of the hundreds of available commands. PowerShell’s support for wildcards helps you narrow your searches. The following example retrieves all the commands that begin with get:
Set-Content—Set-Content (or its alias, sc) is used to write values to a file. If the specified target file doesn’t exist, this command creates it. For example, the following command writes the value “My data” to the file named mynewfile.txt:
sc c:\temp\mynewfile.txt -value “My data”
Get-Content—The counterpart to sc is Get-Content (gc). The gc cmdlet is used to read the contents of a file. For example, the following command displays the contents of the file named mynewfile.txt:
Set-ExecutionPolicy—By default, PowerShell’s ability to run scripts is disabled; you can only enter commands at the command line. The Set-ExecutionPolicy cmdlet lets you change the security level for running scripts. To enable PowerShell to run any script, you can enter the following command:
Set-PsDebug—Although PowerShell doesn’t have a full-featured debugger, it does have basic debugging capabilities through the Set-PsDebug cmdlet. Entering the following command will cause a PowerShell script to step through its execution one line at a time:
Get-Process—PowerShell has great built-in commands that let you perform many tasks that formerly required resource kits or third-party tools. For example, the Get-Process cmdlet retrieves information about the active processes on a system. Use the following example to list all running processes:
Get-Eventlog—The Get-Eventlog cmdlet retrieves Windows event logs. As with Get-Process, there’s no need for additional utilities. The following example shows how you can retrieve the 10 most recent entries from the system event log:
get-eventlog -newest 10 -logname system