The Windows PowerShell Get-Command cmdlet retrieves the names of all available commands. When you type Get-Command at a Windows PowerShell prompt, you will see output similar to the following:
PS> Get-Command CommandType Name Definition ----------- ---- ---------- Cmdlet Add-Content Add-Content [-Path] <String[... Cmdlet Add-History Add-History [[-InputObject] ... Cmdlet Add-Member Add-Member [-MemberType] <PS... ...
This output looks a lot like the Help output of Cmd.exe: a tabular summary of internal commands. In the extract of the Get-Command command output shown above, every command shown has a CommandType of Cmdlet. A Cmdlet is Windows PowerShell's intrinsic command type that corresponds roughly to the dir and cd commands of Cmd.exe and to built-ins in UNIX shells such as BASH.
In the output of the Get-Command command, all the definitions end with ellipses (...) to indicate that PowerShell cannot display all the content in the available space. When Windows PowerShell displays output, it formats the output as text and then arranges it to make the data fit cleanly into the window. We will talk about this later in the section on formatters.
The Get-Command cmdlet has a Syntax parameter that allows you to retrieve just the syntax of each cmdlet. Enter the Get-Command -Syntax command to display the full output:
PS> Get-Command -Syntax Add-Content [-Path] <String> [-Value] <Object> [-PassThru] [-Filter <String>] [-Include <String>] [-Exclude <String>] [-Force] [Credential <PSCredential>] [-Verbose] [-Debug] [-ErrorAction <ActionPreference>] [-ErrorVariable <String>] [-OutVariable <String>] [-OutBuffer <Int32>] [-WhatIf] [-Confirm] [-Encoding <FileSystemCmdletProviderEncoding>] Add-History [[-InputObject] <PSObject>] [-Passthru] [-Verbose] [-Debug] [-ErrorAction <ActionPreference>] [-ErrorVariable <String>] [-OutVariable <String>][-OutBuffer <Int32>]...
Displaying Available Command Types
The Get-Command command does not list every command that is available in Windows PowerShell. Instead, the Get-Command command lists only the cmdlets in the current shell. Windows PowerShell actually supports several other types of commands. Aliases, functions, and scripts are also Windows PowerShell commands, although they are not discussed in detail in the Windows PowerShell User's Guide. External files that are executables, or have a registered file type handler, are also classified as commands.
You can return a listing of all items that can be invoked by entering the following command:
PS> Get-Command *
Because this list includes external files in your search path, it may contain thousands of items. It is more useful to look at a reduced set of commands. To find native commands of other types, you can use the CommandType parameter of the Get-Command cmdlet. Although we have not talked about these other command types yet, you can still display them if you know the name of the CommandType for a class of commands.
Although we have not discussed it yet, the asterisk (*) is used for wildcard matching in Windows PowerShell command arguments. The * means "match one or more of any characters". You can type Get-Command a* to find all commands that begin with the letter "a". Unlike wildcard matching in Cmd.exe, Windows PowerShell's wildcard will also match a period.
To display the special command category aliases (these are nicknames used as alternatives to standard command names), enter the following command:
PS> Get-Command -CommandType Alias
To display all Windows PowerShell functions, enter the following command:
PS> Get-Command -CommandType Function
To display external scripts in Windows PowerShell's search path, enter the following command:
PS> Get-Command -CommandType ExternalScript