What does /v/qn parameter do for windows silent installers?

Question

This page says to do a silent install you pass in the parameters /s /v/qn. It mentions what /s does - silent install - but not what /v/qn does.

So what does it do? Why the weird format? (on one installer I tried /v /qn (with a space) and it didn't work. though on another i also had to do /S (uppercase) and /v/qn didn't seem to do anything.)

Solution

Read the page again.

Passing Data to the Installation

/v : Pass arguments to Msiexec (Basic MSI and InstallScript MSI projects) The /v option is used to pass command-line options and values of public properties through to Msiexec.exe.

So /v/qn will pass /qn onto the embedded MSI installer. The /qn is an msiexec switch indicating to run with no UI. You can find all msiexec switches in this support article.

The "wierd" format is required because that is how the InstallShield command-line parser is programmed to function. Likely, they built it this way to ensure msiexec switches/properties will be unambiguous on the command-line and within scripts.