svnversion is a program for summarizing the revision mixture of a working copy. The resultant revision number, or revision range, is written to standard output.
It’s common to use this output in your build process when defining the version number of your program:
TRAIL_URL, if present, is the trailing
portion of the URL used to determine whether
WC_PATH itself is switched (detection of
WC_PATH does not rely on
WC_PATH is not defined, the current
directory will be used as the working copy path.
TRAIL_URL cannot be defined if
WC_PATH is not explicitly given.