Getting Summary Command Information in Windows PowerShell
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 of the definitions end with ellipses (...) to indicate that PowerShell cannot display all of 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 a console 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>]... |
Windows PowerShell Handles Console Input and Display
When you type a command, Windows PowerShell always processes the command-line input directly. Windows PowerShell also formats the output that you see on the screen. This is significant because it reduces the work required of each cmdlet and ensures that you can always do things the same way regardless of which cmdlet you are using. One example of how this simplifies life for both tool developers and users is command-line help.
Traditional command-line tools have their own schemes for requesting and displaying help. Some command-line tools use /? to trigger the help display; others use -?, /H, or even //. Some will display help in a GUI window, rather than in the console display. Some complex tools, such as application updaters, unpack internal files before displaying their help. If you use the wrong parameter, the tool might ignore what you typed and begin performing a task automatically.
When you enter a command in Windows PowerShell, everything you enter is automatically parsed and pre-processed by Windows PowerShell. If you use the -? parameter with a Windows PowerShell cmdlet, it always means "show me help for this command". Cmdlet developers do not have to parse the command; they only need to provide the help text.
It is important to understand that the help features of Windows PowerShell are available even when you run traditional command-line tools in Windows PowerShell. Windows PowerShell processes the parameters and passes the results to the external tools.
Note:
If you run an graphic application in Windows PowerShell, the window for the application opens. Windows PowerShell intervenes only when processing the command-line input you supply or the application output returned to the console window; it does not affect how the application works internally.
Posted in: Internet Topic| Tags: PowerShell Windows Application Console Handle command cmdlet output help display window inputUnderstanding Important Windows PowerShell Concepts
The Windows PowerShell design integrates concepts from many different environments. Several of them are familiar to people with experience in specific shells or programming environments, but very few people will know about all of them. Looking at some of these concepts provides a useful overview of the shell.
Commands are not Text-based
Unlike traditional command-line interface commands, Windows PowerShell cmdlets are designed to deal with objects - structured information that is more than just a string of characters appearing on the screen. Command output always carries along extra information that you can use if you need it. We will discuss this topic in depth in this document.
If you have used text-processing tools to process command-line data in the past, you will find that they behave differently if you try to use them in Windows PowerShell. In most cases, you do not need text-processing tools to extract specific information. You can access portions of the data directly by using standard Windows PowerShell object manipulation commands.
The Command Family is Extensible
Interfaces such as Cmd.exe do not provide a way for you to directly extend the built-in command set. You can create external command-line tools that run in Cmd.exe, but these external tools do not have services, such as help integration, and Cmd.exe does not automatically know that they are valid commands.
The native binary commands in Windows PowerShell, known as cmdlets (pronounced command-lets), can be augmented by cmdlets that you create and that you add to Windows PowerShell by using snap-ins. Windows PowerShell snap-ins are compiled, just like binary tools in any other interface. You can use them to add Windows PowerShell providers to the shell, as well as new cmdlets.
Because of the special nature of the Windows PowerShell internal commands, we will refer to them as cmdlets.
Posted in: Internet Topic| Tags: Interface PowerShell Windows Concept Important command information toc name exe cmd shellWindows PowerShell Basics
Graphical interfaces use some basic concepts that are well known to most computer users. Users rely on the familiarity of those interfaces to to accomplish tasks. Operating systems present users with a graphical representation of items that can be browsed, usually with drop-down menus for accessing specific functionality and context menus for accessing context-specific functionality.
A command-line interface (CLI), such as Windows PowerShell, must use a different approach to expose information, because it does not have menus or graphical systems to help the user. You need to know command names before you can use them. Although you can type complex commands that are equivalent to the features in a GUI environment, you must become familiar with commonly-used commands and command parameters.
Most CLIs do not have patterns that can help the user to learn the interface. Because CLIs were the first operating system shells, many command names and parameter names were selected arbitrarily. Terse command names were generally chosen over clear ones. Although help systems and command design standards are integrated into most CLIs, they have been generally designed for compatibility with the earliest commands, so the command set is still shaped by decisions made decades ago.
Windows PowerShell was designed to take advantage of a user's historic knowledge of CLIs. In this chapter, we will talk about some basic tools and concepts that you can use to learn Windows PowerShell quickly. They include:
· Using Get-Command
· Using Cmd.exe and UNIX commands
· Using External Commands
· Using Tab-Completion
· Using Get-Help
Posted in: Internet Topic| Tags: Interface PowerShell Windows Basic user clis operating basics functionality graphical command