;if this old version of this file exists
If EXIST = ("C:\program files\[a certain program]\[a certain file]")
	?"Removing old program"
	RUN ("C:\WINDOWS\IsUninst.exe -y -a -f"C:\Program Files\[a certain program\a certain uninstall file location]\Uni114.isu" ")
	?"Installing new program"
	RUN (""\\network_path_to_current_file_server\newprogram.msi" /s")
EndIf

If EXIST("C:\program files\[a certain program]\[a certain file]")
   "Removing old program"+@CRLF
   Shell 'C:\WINDOWS\IsUninst.exe -y -a -f"C:\Program Files\[a certain program\a certain uninstall file location]\Uni114.isu"'
   "Installing new program"+@CRLF
   Shell '"\\network_path_to_current_file_server\newprogram.msi" /s'
EndIf

Quote:

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second, a question about run; does run wait until the execution is done, or does the script continue directly?

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