Powershell to install Farm solutions (wsp) [duplicate]

Question

we are trying to deploy farm solution wsp file on the SharePoint server via PowerShell. The wsp is a webpart. I got this script by browsing forums...

Foll. is our code:-

$oUrl="http://mysite:9999/"    
$solutionPath="C:\MySolutions\"

$solution="FarmSolution.wsp"
$path= $solutionPath + $solution 
Add-SPSolution -LiteralPath $path
install-spsolution -Identity $solution -WebApplication $oUrl -GACDeployment 
WaitForJobToFinish

Using the above PowerShell the wsp gets successfully deployed into the GAC. The webpart can then be added to page and used successfully.

My question is on the foll. line:-

install-spsolution -Identity $solution -WebApplication $oUrl -GACDeployment 

Since the wsp gets deployed to the GAC, then what is purpose of using -WebApplication $oUrl. Can I remove this part? Generally, the only purpose of using the -WebApplication $oURL without following -GACDeployment is to deploy the wsp to inetpub/site/bin.

Now, if our goal is to deploy the wsp to GAC, then why not use it as:-

install-spsolution -Identity $solution -GACDeployment 

Would this be correct?

This question doesnt look to be duplicate of this link as the question addresses the concern of using either -WebApplication or -GACDeployment or both together in powershell to deploy an feature. Also, the answer shows that the value of the 3rd column (Depyoled To) under Manage farm solutions depends upon the use of -WebApplication or -GACDeployment in powershell while deploying as explained by @Waqas Sarwar MCSE which I have marked as an answer.

Answer 1

we use the webapplication switch, if you want to target one web application(Deploys the SharePoint solution for the specified SharePoint web application.)...i.e we have 4 web applications and i want to deploy the solution on 1 web application only, then i will use the this switch, otherwise the webapplication it will deploy the solution to all web application.

GAC deployment means solution available for everybody but it does not mean that every body can use it unless you install it for every web app.

Deploy solution packages (SharePoint Server 2010)

Answer 2

Since your WSP contains a webpart, it has safe control entries. And safe control entries are added to web.config files. Generally you make a check while deploying the solutions:

if($Solution.ContainsWebApplicationResource)   
{
    Install-SPSolution -Identity $SolutionPackageName -WebApplication $WebApplication -  GACDeployment -Confirm:$false
}
else
{
    Install-SPSolution -Identity $SolutionPackageName -GACDeployment -Confirm:$false
}

You can very well remove the -WebApplication parameter from a solution which has web application resources. In that case safe control entries will be added to all web.config files of all web applications. However, if you try to deploy a solution with no such resoureces using -WebApplication aparemeter it will give error that "this solution contains no resources scoped for a web application"

Answer 3

In short, yes because it's an optional parameter,

WebApplication

Optional

Microsoft.SharePoint.PowerShell.SPWebApplicationPipeBind

Deploys the SharePoint solution for the specified SharePoint web application. The value must be in one of the following forms:

An authentic GUID, in the form 12345678-90ab-cdef-1234-567890bcdefgh

An authentic name of a SharePoint web application (for example, MyOfficeApp1)

An instance of an authentic SPWebApplication object.

Reference

If you won't going to provide WebApplication parameter, it will deploy solution to all web application.

This parameter is useful when your solution or feature is SPWebApplication scope and it going to make changes to specific web application. For example web.config changes, as said by Nadeem.

Edit

Saying all that documented, it's not easy to understand, here is an example I came across in past,

Moss Timer job deployed in one web application but running in a different web application