The batch file has to be started in a new command shell. So the custom action is the
cmd.exe executable with the batch file as argument:
[SystemFolder]\cmd.exe /c full_path_of_batch_file
Similar can be used for MySQL scripts where
mysql.exe must be also started via
cmd.exe to allow input redirection:
[SystemFolder]\cmd.exe /c "full_path_of_mysql.exe < full_path_of_sql_script"
Or just put the script execution into another batch file if you know the pathes in advance.
Can be all found by web research:
execute .BAT file in installshield - Stack Overflow[
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InstallShield 2014, Custom Actions and executing sql files into MySQL - Stack Overflow[
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