Powershell understanding piping with Get-SPSite/Get-SPWeb?

Question

I wanted to get a list of all webs within a web application. By accident I wrote the following:

$webapp = "http://mywebapp"
$webapp | Get-SPSite | Get-SPWeb

So, this returned fantastic results, giving me the URLs of each web in the web app. But the powershell command doesn't make sense to me.

I actually meant to write something like:

$webapp = "http://mywebapp"
Get-SPWebApplication $webapp | Get-SPSite | Get-SPWeb

which produces the same results. Does it just take the url at face value and intelligently assume it's a web app url? I'm guessing it converts it to an SPWebApplication object, and pipes that to Get-SPSite, which gets each site collection object within the web app, etc..

Answer 1

The pipeline passes one object of a command to another. The result of the first command is an input for the next command.

So in your example The first command Generated List of SPWebApplication which is passed to Get-SPSite etc

http://technet.microsoft.com/en-us/library/ff607950%28v=office.15%29.aspx

http://blogs.catapultsystems.com/SSamuel/archive/2012/10/15/using-pipes-in-powershell-tip-1.aspx

From the technet article of Get-SPSite - The Get-SPSite cmdlet returns either a single site that matches the Identity parameter, or all the sites that match the Filter parameter for the specified scope. The scopes are the WebApplication, ContentDatabase , and SiteSubscription parameters. If none of these scopes is provided, the scope is the farm. If the scope is specified with no Filter parameter, all sites in that scope are returned.

So it can be piped from SPWebApplication, SPContentDatabase, and SPSiteSubscription

Get-SPContentDatabase | Get-SPSite