$ xstructural validate --sourceFile com.io7m.xstructural.documentation/target/documentation/main.xml
xstructural: XSValidator: INFO: validate (xstructural) /home/user/xstructural/com.io7m.xstructural.documentation/target/documentation/main.xml

$ echo $?
0

$ xstructural validate --sourceFile README-CHANGES.xml
xstructural: XSValidator: INFO: validate (xstructural) /home/user/xstructural/README-CHANGES.xml
xstructural: validation: ERROR: file:///home/user/xstructural/README-CHANGES.xml:2:82: cvc-elt.1.a: Cannot find the declaration of element 'c:changelog'.
xstructural: XSValidator: ERROR: one or more validation errors occurred
xstructural: Main: ERROR: com.io7m.xstructural.api.XSValidationException: Document /home/user/xstructural/README-CHANGES.xml is not a valid structural document

$ echo $?
1
