Provided by: syncmaildir_1.3.0-1_amd64 bug


       mddiff - computes diff for maildirs


       mddiff [--max-mailno mno] [--db-file dbf] [-l|--list] [-s|--symlink]
              [--exclude globexpr] [-v|--verbose] [-d|--dry-run]
              [-n|--no-delete] [--no-move] [--help] [--sha1sum] paths


       mddiff  computes  the  delta  from  an  old  status of a maildir (previously recorded in a
       support file, called db file) and the current status, generating  a  set  of  commands  (a
       diff)  that  a third party software can apply to synchronize a (eventually remote) copy of
       the maildir.

       If paths is a single file name, and that file is a fifo, mddiff reads from it  file  names
       separated by new line and outputs the sha1 of its header and body separated by space.

             $ mddiff /tmp/fifo_for_mddiff
             806a0ffe4f29766effd764... 463e543da9dac8e298...
             582cbb6a5cd3ce13965c8c... 8fa60a7458b1157193...

       If  paths  is  a  single  file name, and that file is a fifo, and the -s option is passed,
       mddiff reads from that fifo two lines at a time, respectively a source name and  a  target
       name.  It  then creates a symlink named as as the target name pointing to the source name.
       If some dictories need to be created in order to create the symlink, this  is  also  done.
       mddiff will print 'OK' on stdout to signal a success, 'ERROR' to signal an error.

       If  paths  is  a  list  of  directories,  mddiff outputs a list of actions a client has to
       perform to synchronize a copy of the same maildirs. This set of actions is relative  to  a
       previous status of the maildir stored in the db file.  The input directories are traversed
       recursively, and every file encountered inside  directories  named  cur/  and  new/  is  a
       potential mail message (if it contains no \n\n it is skipped).

             $ mddiff ~/Mail/
             ADD ~/Mail/cur/1239038050.14937_1.garfield:2,S 66532ebb05b252e...

       Every client (endpoint using mddiff for synchronization) must use a different db-file, and
       the db-file is strictly related with the set of directories given as arguments, and should
       not  be  used  with  a different directory set. Adding items to the directory set is safe,
       while removing them may not do what you want (delete actions are generated).

       mddiff does not alter the dbf file, it generates a new one called  It  is  up  to
       the  higher  level  tool smd-server(1) to rename to dbf in case the other endpoint
       successfully applied the diff.

       The --exclude option  tells  mddiff  to  ignore  all  paths  matching  the  given  glob(7)
       expression.  This  option  can  be  passed  multiple  times.  Matching  is performed using
       fnmatch(3) with no special flags, thus '*' and '?'  match  any  character  including  '/'.
       Matching  is  performed  when  a  directory  is  entered.  If the match is successful, the
       directory and all its subedirectories are skipped.

       The --no-delete option tells  mddiff  to  not  output  a  DELETE  action  for  files  that
       disappear.  Note  that  a DELETE action is anyway generated for files that are moved (i.e.
       move is COPY plus DELETE). The result is that deletions are not propagated  to  the  other


       --max-mailno mno
              Estimation  of  max  mail message number (defaults to the number of messages in the
              db-file + 1000 or 500000 if there is no db-file). You may want to decrease  it  for
              the first run on small systems. It is anyway increased automatically when needed

       --db-file dbf
              Name of the cache for the endpoint (default db.txt)

       --exclude globexpr
              Exclude paths maching the given expression

              Behaves like the sha1sum utility

              Behaves like mkdir -p

              Behaves like mkfifo

       -l --list
              Only list the mailboxes recursively contained in paths

       -s --symlink
              Create symlinks for paths read on the input fifo

       -v --verbose
              Increase program verbosity (printed on stderr)

       -d --dry-run
              Do not generate a new db-file

       -n --no-delete
              Do not track deleted files

              Do not generate MOVE (only COPY + DELETE)

       --help This help screen


       mddiff  is  a  low level utility, used by smd-server and smd-client. You should use higher
       level tools like smd-pull(1), smd-push(1) and smd-loop(1)


       smd-client(1), smd-server(1), smd-pull(1), smd-push(1), smd-loop(1)


       Enrico Tassi <>

                                          17 March 2018                                 mddiff(1)