** 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
**   --checkin VERSION          Show diff of all changes in VERSION
**   --command PROG             External diff program - overrides "diff-command"
**   --context|-c N             Use N lines of context
**   --diff-binary BOOL         Include binary files when using external commands
**   --exec-abs-paths           Force absolute path names with external commands.
**   --exec-rel-paths           Force relative path names with external commands.
**   --from|-r VERSION          Select VERSION as source for the diff
**   --internal|-i              Use internal diff logic
**   --new-file|-N              Show complete text of added and deleted files
**   --numstat                  Show only the number of lines delete and added
**   --side-by-side|-y          Side-by-side diff
**   --strip-trailing-cr        Strip trailing CR
**   --tclsh PATH               Tcl/Tk used for --tk (default: "tclsh")
**   --tk                       Launch a Tcl/Tk GUI for display
**   --to VERSION               Select VERSION as target for the diff
**   --undo                     Diff against the "undo" buffer
**   --unified                  Unified diff
**   -v|--verbose               Output complete text of added or deleted files
**   -w|--ignore-all-space      Ignore white space when comparing lines
**   -W|--width <num>           Width of lines in side-by-side diff
**   -Z|--ignore-trailing-space Ignore changes to end-of-line whitespace
**   --binary PATTERN            Treat files that match the glob PATTERN
**                               as binary
**   --branch BRANCH             Show diff of all changes on BRANCH
**   --brief                     Show filenames only
**   --checkin VERSION           Show diff of all changes in VERSION
**   --command PROG              External diff program. Overrides "diff-command"
**   --context|-c N              Use N lines of context
**   --diff-binary BOOL          Include binary files with external commands
**   --exec-abs-paths            Force absolute path names on external commands
**   --exec-rel-paths            Force relative path names on external commands
**   --from|-r VERSION           Select VERSION as source for the diff
**   --internal|-i               Use internal diff logic
**   --new-file|-N               Show complete text of added and deleted files
**   --numstat                   Show only the number of lines delete and added
**   --side-by-side|-y           Side-by-side diff
**   --strip-trailing-cr         Strip trailing CR
**   --tclsh PATH                Tcl/Tk used for --tk (default: "tclsh")
**   --tk                        Launch a Tcl/Tk GUI for display
**   --to VERSION                Select VERSION as target for the diff
**   --undo                      Diff against the "undo" buffer
**   --unified                   Unified diff
**   -v|--verbose                Output complete text of added or deleted files
**   -w|--ignore-all-space       Ignore white space when comparing lines
**   -W|--width N                Width of lines in side-by-side diff
**   -Z|--ignore-trailing-space  Ignore changes to end-of-line whitespace
*/
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 */