** the "setting" command.  If no external diff program is configured, then
** the "-i" option is a no-op.  The "-i" option converts "gdiff" into "diff".
**
** The "-N" or "--new-file" option causes the complete text of added or
** deleted files to be displayed.
**
** Options:
**   --branch BRANCH     Show diff of all changes on BRANCH
**   --brief             Show filenames only
**   --context|-c N      Use N lines of context 
**   --from|-r VERSION   select VERSION as source for the diff
**   -i                  use internal diff logic
**   --new-file|-N       output complete text of added or deleted files
**   --to VERSION        select VERSION as target for the diff
**   --side-by-side|-y   side-by-side diff
**   --width|-W N        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 hasNFlag;              /* True if -N or --new-file flag is used */
  const char *zFrom;         /* Source version number */
  const char *zTo;           /* Target version number */
  const char *zBranch;       /* Branch to diff */
  const char *zDiffCmd = 0;  /* External diff command. NULL for internal diff */
  int diffFlags = 0;         /* Flags to control the DIFF */
  int f;

  isGDiff = g.argv[1][0]=='g';
  isInternDiff = find_option("internal","i",0)!=0;
  zFrom = find_option("from", "r", 1);
  zTo = find_option("to", 0, 1);
  zBranch = find_option("branch", 0, 1);
  diffFlags = diff_options();
  hasNFlag = find_option("new-file","N",0)!=0;
  if( hasNFlag ) diffFlags |= DIFF_NEWFILE;

  if( zBranch ){
    if( zTo || zFrom ){
      fossil_fatal("cannot use --from or --to with --branch");
    }
    zTo = mprintf("tag:%s", zBranch);
    zFrom = mprintf("root:%s", zBranch);
  }
  if( zTo==0 ){
    db_must_be_within_tree();
    verify_all_options();
    if( !isInternDiff ){
      zDiffCmd = db_get(isGDiff ? "gdiff-command" : "diff-command", 0);
    }
    if( g.argc>=3 ){