** when using an external diff program.
**
** The "--binary" option causes files matching the glob PATTERN to be treated
** as binary when considering if they should be used with external diff program.
** This option overrides the "binary-glob" setting.
**
** Options:
**   --binary PATTERN       Treat files that match the glob PATTERN as binary
**   --branch BRANCH        Show diff of all changes on BRANCH
**   --brief                Show filenames only
**   --context|-c N         Use N lines of context
**   --diff-binary BOOL     Include binary files when using external commands
**   --from|-r VERSION      select VERSION as source for the diff
**   --ignore-space-at-eol  Ignore changes to end-of-line whitespace
**   --ignore-space-at-sol  Ignore changes to start-of-line whitespace
**   --internal|-i          use internal diff logic
**   --side-by-side|-y      side-by-side diff
**   --tk                   Launch a Tcl/Tk GUI for display
**   --to VERSION           select VERSION as target for the diff
**   --unified              unified diff
**   -v|--verbose           output complete text of added or deleted files
**   -w                     Ignore changes to start-of-line and end-of-line
**                          whitespace
**   -W|--width             Width of lines in side-by-side diff

*/
void diff_cmd(void){
  int isGDiff;               /* True for gdiff.  False for normal diff */
  int isInternDiff;          /* True for internal diff */
  int verboseFlag;           /* True if -v or --verbose flag is used */
  const char *zFrom;         /* Source version number */
  const char *zTo;           /* Target version number */