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Adding changes discussed

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1. Added info on scoping with dot sourcing, IEX, and call operator
2. Added comments about .NET class calling
3. Changed Get-EventLog to Get-WinEvent
4. Added info on Pipeline caveats related to passing bytes and speed
5. Added in a couple more pipeline examples to iteration and filtering

And some formatting changes
This commit is contained in:
Andrew Ryan Davis 2020-08-19 14:14:47 -07:00
parent cf5b2a36e0
commit eeaff3bc70
1 changed files with 40 additions and 5 deletions
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@ -18,7 +18,7 @@ rather than plain text. After years of evolving, it resembles Python a bit.
[Read more here.](https://docs.microsoft.com/powershell/scripting/overview)
Powershell as a Language:
<H3>Powershell as a Language:</H3>
```powershell
@ -116,6 +116,8 @@ $False - 5 # => -5
# (-is vs. -eq) -is checks if two objects are the same type
# -eq checks if the objects have the same values.
# Note: we called '[Math]' from .NET previously without the preceeding
# namespaces. We can do the same with [Collections.ArrayList] if preferred
[System.Collections.ArrayList]$a = @() # Point a at a new list
$a = (1,2,3,4)
$b = $a # => Point b at what a is pointing to
@ -541,7 +543,7 @@ True False Guitar Instrument
## 7. Advanced
####################################################
# The powershell pipeline allows us to do things like High-Order Functions
# The powershell pipeline allows things like High-Order Functions
# Group Object is a handy command that does incredible things for us
# It works much like a GROUP BY in SQL would
@ -554,6 +556,16 @@ True False Guitar Instrument
#>
Get-Process | Foreach-Object ProcessName | Group-Object
# Useful pipeline examples are iteration and filtering
1..10 | ForEach-Object { "Loop number $PSITEM" }
1..10 | where {$PSITEM -gt 5} | Format-Table
# A noteable pitfall of the pipeline is it's performance when
# compared with other options
# additionally, raw bytes are not passed through the piipeline
# so passing an image causes some issues
# See more on that in the links at the bottom
<#
Asynchronous functions exist in the form of jobs
Typically a procedural language
@ -633,7 +645,7 @@ function Format-Range ($start, $end) {
Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m','n'
```
Powershell as a Tool:
<H3>Powershell as a Tool:</H3>
Getting Help:
@ -647,7 +659,7 @@ Get-Alias -Definition Get-Process
Get-Help ps | less # alias: help
ps | Get-Member # alias: gm
Show-Command Get-EventLog # Display GUI to fill in the parameters
Show-Command Get-WinEvent # Display GUI to fill in the parameters
Update-Help # Run as admin
```
@ -668,10 +680,32 @@ $PSVersionTable
```
```Powershell
# Calling external commands, executables, and functions with the call operator.
# the call operator (&) is similar to Invoke-Expression, but IEX runs in current scope.
# Standard usage of '&' would be to invoke a scriptblock inside of your script.
# Notice the variables are scoped
$i = 2
$scriptblock = { $i=5; Write-Output $i }
& $scriptblock # => 5
$i # => 2
invoke-expression ' $i=5; Write-Output $i ' # => 5
$i # => 5
# Alternatively, to preserve changes to public variables
# you can use "Dot-Sourcing". This will run in the current scope
$x=1
&{$x=2};$x # => 1
. {$x=2};$x # => 2
# Remoting into computers is easy
Enter-PSSession -ComputerName RemoteComputer
# Once remoted in, you can run commands as if you're local
RemoteComputer\PS> Get-Process powershell
<#
Handles NPM(K) PM(K) WS(K) CPU(s) Id SI ProcessName
------- ------ ----- ----- ------ -- -- -----------
@ -727,7 +761,7 @@ foreach ($server in $serverList) {
Interesting Projects
* [Channel9](https://channel9.msdn.com/Search?term=powershell%20pipeline#ch9Search&lang-en=en) PowerShell tutorials
* [KevinMarquette's Powershell Blog](https://powershellexplained.com/) Really excellent blog that goes into great detail on Powershell
* [KevinMarquette's Powershell Blog](https://powershellexplained.com/) Excellent blog that goes into great detail on Powershell
* [PSGet](https://github.com/psget/psget) NuGet for PowerShell
* [PSReadLine](https://github.com/lzybkr/PSReadLine/) A bash inspired readline implementation for PowerShell (So good that it now ships with Windows10 by default!)
* [Posh-Git](https://github.com/dahlbyk/posh-git/) Fancy Git Prompt (Recommended!)
@ -736,3 +770,4 @@ Interesting Projects
* [Pester](https://github.com/pester/Pester) BDD Testing Framework
* [Jump-Location](https://github.com/tkellogg/Jump-Location) Powershell `cd` that reads your mind
* [PowerShell Community Extensions](https://github.com/Pscx/Pscx)
* [More on the Powershell Pipeline Issue](https://github.com/PowerShell/PowerShell/issues/1908)