1. Cmdlets “Command-lets”
PowerShell
Cmdlets “Command-lets”
Copyright © 2016 – Curt Hill

2. Introduction Previously, we considered:
Similarity of PowerShell to the DOS Command Box
Scripting basics
Scripting flow of control
Now we examine in more detail the notion of a cmdlet
These are lightweight commands that perform an action and usually return a .NET object
Copyright © 2016 – Curt Hill

3. Differences From Commands
Cmdlets are instances of .NET Framework classes
Not stand-alone executables
Cmdlets usually do not parse, display errors, or format output
This is handled by PowerShell
Cmdlets process input objects rather than streams of text
Cmdlets are record-oriented because they process a single object at a time
Object may contain several things
Copyright © 2016 – Curt Hill

4. Form Cmdlets use a verb-noun pair to identify a cmdlet
These are followed by options or items to act upon
An alias may exist that makes the cmdlet resemble a previous DOS command
Lets consider the copy-item cmdlet
Copyright © 2016 – Curt Hill

5. Copy-Item Takes two strings as parameters
The copy from string
The copy to string
Both should refer to one or more files
Wildcards may be used
The aliases include Cp
Copy
Cpi
Options include
-recurse
Copyright © 2016 – Curt Hill

6. Aliases These are provided to make it more convenient for users
Especially from other systems
The COPY-ITEM cmdlet has as aliases the following:
CP – for UNIX/LINUX users
CPI – just an appreviation
COPY – for DOS users
Copyright © 2016 – Curt Hill

7. Item In the previous cmdlet there were two pieces What is an Item?
The verb was Copy
The noun was Item
What is an Item?
It could be:
Variable
File
Among others
Copyright © 2016 – Curt Hill

8. Item Verbs Get – gives entries for files Move – Copy + delete original
Similar to get-childitem, which also shows subdirectories
If you give it a variable it interprets as file
Move – Copy + delete original
New – creates a new file
Use –type directory for a new directory
Remove – deletes
Use –recurse to remove subdirectories
Rename – Guess what this does
Copyright © 2016 – Curt Hill

9. Assignment Not only will a cmdlet do some useful action
It may also be used to produce values for variable
It can be saved in variable using: $files = get-childitem
Wildcards could be used after get-childitem
Copyright © 2016 – Curt Hill

10. Piping As in DOS the vertical bar (|) is the pipe directive
This transfers the output of one program into the input of another
This is frequently done with cmdlets as well
We will see examples later
Copyright © 2016 – Curt Hill

11. Perhaps Useful Cmdlets
Add-content file data
Append the data to the end of a file
Clear-content file
Empties a file, but does not erase
Compare-object
Shows what is in one or other
Does not show both
Two should be same type
Copyright © 2016 – Curt Hill

12. More Cmdlets Get-content file Set-content file Test-path file
Gets the file content
Set-content file
Creates file if needed
Test-path file
Returns true if file exists
Wildcards may be used
Write-host
Displays strings to console
Copyright © 2016 – Curt Hill

13. Content The {Add|Clear|Get|Set}-Content only works well for text files
Any specialized format will likely be damaged by Add, Clear or Set and return garbage for Get
Copyright © 2016 – Curt Hill

14. Convert to HTML Yes this is a cmdlet
Any command that produces a display may be piped into this
The result may be manipulated further or set into a file
Here are two screen shots
Copyright © 2016 – Curt Hill

15. Creating HTML
Copyright © 2016 – Curt Hill

16. Viewing
Copyright © 2016 – Curt Hill

17. Help
The cmdlet get-command lists all the cmdlets available on this system
There are typically hundreds
Use Help and the cmdlet name to find out more about each
If you need more help still use the –online parameter
This will take you to a web site
Copyright © 2016 – Curt Hill

18. More Help You can find the files in a directory
Use get-item or get-childitem
What can be done with this information?
Pipe it into get-member
This will show the properties and methods
Copyright © 2016 – Curt Hill

19. Properties and Methods
Any variable may contain an object of any number of types
It depends how the variable was set
Get-member shows the available properties and methods
A property or method is used by following the item with a dot and then giving the property or method name
A method must be followed by parenthesis
Usually empty
Copyright © 2016 – Curt Hill

20. Example In this example the following will be done
The get-item cmdlet will find the information on .PPT files in a directory
It will assign to a variable
The properties and methods of that data will be shown
Two properties and one method will be exercised
This will use 5 screen shots
Copyright © 2016 – Curt Hill

21. Assigning
Copyright © 2016 – Curt Hill

22. Finding Members
Copyright © 2016 – Curt Hill

23. Finding Again
Copyright © 2016 – Curt Hill

24. Properties
Copyright © 2016 – Curt Hill

25. Methods
Copyright © 2016 – Curt Hill

26. Finally As you can see there is lots more to know
What we need now is a demonstration
Then an exercise
We will need to look at parameters and scope
Then an assignment
Copyright © 2016 – Curt Hill