In an InstallScript custom action, you can call SprintfMsiLog to write a string to the MSI log
file. For example, the following InstallScript code prototypes and defines an InstallScript
custom action called LoggingTestInstallScript.
// standard custom action prototype
export prototype LoggingTestInstallScript(HWND);
// custom action definition
// return success to MSI
In order to be called, the custom action must be scheduled in the sequences. For this
example, open the Custom Actions view and create an immediate-mode InstallScript custom
action called callLoggingTest that calls the LoggingTestInstallScript function, and schedule it
to run after LaunchConditions.
After building the package and running it with the /L*v switch, you should see a line similar
to the following in the log file:
InstallShield 25:00:00: Invoking script function LoggingTestInstallScript
1: Calling LoggingTestInstallScript...
InstallShield 25:00:00: CallScriptFunctionFromMsiCA() ends
Action ended 25:00:00: callLoggingTest. Return value 1.
The SprintfMsiLog function is similar to the Sprintf and SprintfBox functions, in that you can
include placeholders ("%s" or "%d" fields, called "format specifiers") in the message string
if you want to splice in the values of string or numeric variables.