To run an unattended installation
The -f1 <initialization file path> argument selects an unattended setup initialization file.
The start /wait command, together with the -SMS option, return control to the command prompt only after SQL Server Setup finishes.
The -s flag causes the setup program to run in silent mode with no user interface.
start /wait D:\x86\setup\setupsql.exe -f1 C:\InstallScripts\SQL7.iss -SMS -s