The Object Pipeline is one of the most useful and coolest technologies you may ever hope to see.
It is the jewel in PowerShell’s crown.
In the real world, a pipeline will let a liquid or a gas flow through it effeciently.
In PowerShell, the object pipeline allows objects to flow thru from step to step, so we can use PowerShell fluidly.
Pipelines are a series of expressions or commands, separted by a pipe character |, and you’d be positively amazed how much you can string together with one little pipeline.
For instance, let’s get all commands, pick a random one, and get help:
Get-Command |
Get-Random |
Get-Help
PowerShell includes many built-in -Object commands that will help you manipulate any object, no matter what produced it.
You’ll probably use two of these more than any other: Foreach-Object (aliased to %) and Where-Object (aliased to ?).
Let’s find all processes using more than 100 megabytes of memory.
Get-Process |
Where-Object WorkingSet -gt 100mb
This is an elegantly simple way to script.
It certainly beats the alternative.
Some languages, like Bash, include a text based pipeline.
In this sort of a pipeline, each step has to figure out how to extract useful information from the text in the previous step.
This is why dealing with a text pipeline is known as “parsing and praying”.