A method for controlling execution of a script program programmed to install a computer program is disclosed. An installation computer begins execution of the script program, and before a line or stanza of the script program is executed to initiate installation of the computer program, the installation computer determines that the line or stanza is programmed to initiate installation of the computer program. In response, the installation computer determines if the computer program is already installed. If the computer program is already installed, the installation computer skips the line or stanza of the script program so the script program will not attempt to install the computer program. However, if not, the installation computer continues to execute the script program including the line or stanza programmed to initiate installation of the computer program, such that the script program attempts to install the computer program.