The Silent Install options for the NSIS installer

You can manually search for silent installation keys (e.g. /s, /q, /quiet) or use Silent Install Builder 6, which automatically detects parameters, generates a script, and saves you time. /how-to-find-silent-install-arguments

/SRuns the installer in silent mode
/SDComplitely silent mode. Supress messageboxes.
/DSpecifies the installation directory.

Example

Silently install the program:

setup.exe /S

Silently install the program in to directory C:\Program Files\Setup:

setup.exe /S /D="C:\Program Files\Setup"

If the application does not have silent installation keys, read the guide with proven methods [How to Install Software Silently, Even If It Doesn’t Support Silent Mode].