Currently you can specify a script to call by simply removing the extension and XShell will automatically add .cmd on Windows. Not sure why .sh is not getting added on Linux because it should be mostly the default extension for bash scripts.

Also would it be possible to not only add the default extension but also check for alternatives? Batch files on Windows have a .cmd extension nowadays, and not sure what options exist on Linux. So would be great if the plugin could support multiple extensions, select the best match or fails when executing the shell if multiple matches exist which can't be resolved.