mddiff - computes diff for maildirs

       Enrico Tassi <gares@fettunta.org>

                                                  01 April 2024                                        mddiff(1)

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 dbf.new.  It is up to the higher level
       tool smd-server(1) to rename dbf.new 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 endpoint.

mddiff - computes diff for maildirs

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)

--max-mailnomno
              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-filedbf
              Name of the cache for the endpoint (default db.txt)

       --excludeglobexpr
              Exclude paths maching the given expression

       --sha1sum
              Behaves like the sha1sum utility

       --mkdir-p
              Behaves like mkdir -p--mkfifo
              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

       --no-move
              Do not generate MOVE (only COPY + DELETE)

       --help This help screen

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

mddiff [--max-mailnomno] [--db-filedbf] [-l|--list] [-s|--symlink]
              [--excludeglobexpr] [-v|--verbose] [-d|--dry-run]
              [-n|--no-delete] [--no-move] [--help] [--sha1sum] paths