From Xojo Documentation
Property (As String )
| This property is only available on macOS and Linux platforms.
For cross-platform compatibility, use ＃If...＃Endif with the Target... specifiers to make sure you will not attempt to use this property on an incompatible platform.
Changes the shell backend that is used. The default is "bash". This property applies only to Linux and macOS.
Change the Shell backend to Bourne Shell (if available):