How do I know that script completed successfully?

You can tell the result of script by WinSCP exit code. Code 0 indicates success, while 1 indicates an error.

Batch script (specified using /script or /command command-line switches) terminates with code 1 immediately once any error occurs. You can change this using option batch command.

To find out why the script failed, inspect session log.

For an example see:

• Guide to transfer automation;
• Retrying script/connection attempt example;
• Emailing script results example.

If you need a better control of error handling, consider using WinSCP .NET assembly instead (e.g. from a PowerShell script).