1. PowerShell
Introduction
Copyright © 2016 – Curt Hill

2. Shells
The notion of a shell dates back to early versions of UNIX or before
A shell is a command interpreter
It gave an interactive means for a user to use the system
UNIX allowed anyone to create their own shell, while Windows was less forthcoming in this respect
On most versions of Windows this is the DOS command prompt
Copyright © 2016 – Curt Hill

3. Shell Scripts
If the shell can accept commands from a file instead of the console this is called a shell script
UNIX had a command redirection feature that enabled this
The > and < on the prompt
A shell script is a full but simple programming language with variables, flow of control and other features we expect in programming languages
Copyright © 2016 – Curt Hill

4. Microsoft Batch Files
The batch language of Windows (and previously DOS) is the script
It allowed execution of programs and added the features of a programming language such as comments, variables, decision and looping statements
Compared to UNIX/LINUX shell scripts these were unsatisfactorily weak
You should have been exposed to batch files previously
Copyright © 2016 – Curt Hill

5. PowerShell History
The problems with batch files caused MS to develop a new shell named PowerShell that was released in 2006
This same project had previously been released as a beta under the name Monad as early as 2003
Several releases followed
In 2016 MS made it open source and had ported it to other platforms such as LINUX and OS X
Too soon to tell if it will be widely adopted outside of Windows
Copyright © 2016 – Curt Hill

6. What is PowerShell?
A task automation and configuration management tool
It is a command-line shell and a language
Designed to allow system administrators to perform tasks on both local and networked devices
Based on the .NET framework
This makes the portability easier
Copyright © 2016 – Curt Hill

7. In Windows Windows 10, by default, has PowerShell
In previous versions it required a separate, but free, installation
Copyright © 2016 – Curt Hill

8. Execution Two possibilities
A DOS like resizable window
A script file
There are four types of commands that may be executed:
Executable files on the path
Cmdlets (pronounced command-lets)
PowerShell script files (.ps1 extension)
PowerShell functions
Further examination of these is in order
Copyright © 2016 – Curt Hill

9. Window PowerShell is in the Windows 10 menu of all applications
Under Windows not Microsoft
Clicking on it gives the possibility of the next two screens
Copyright © 2016 – Curt Hill

10. Windows 10 Menu
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11. In Action
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12. Notice
The prompt looks like a DOS prompt except that it is prefixed by a PS
Default background is blue rather than black
In this picture are two commands that are the same in either DOS or PowerShell
D: to change default disk
cd to change directory
The prompt has the PS as well as disk and directory
Copyright © 2016 – Curt Hill

13. From DOS Box You may also execute the PowerShell from the DOS box
But why?
In that case PowerShell takes over the DOS box
See next slide
Copyright © 2016 – Curt Hill

14. PS from DOS
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15. Commentary The exit command works in PowerShell similarly to DOS
The cd command changed PowerShell’s current directory, but not that of the enclosing DOS box
Copyright © 2016 – Curt Hill

16. Finally for Now
As you can see PowerShell has much in common with the DOS box
We will consider the newer and better features in subsequent presentations
Of course, we must have a PowerShell assignment!
Copyright © 2016 – Curt Hill