- Simple configuration copying/moving files from one directory
     to another locally

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        /home/afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://local//home/afd/data/out

     shorter form:

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out


   - Send one file to multiple destinations

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out1
                 file://afd@local/data/out2
                 sftp://afd@local/data/out3
                 ftp://ftponly:secret@local/data/out4

                 [options]
                 create target dir

     Send different data to different destinations

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           out1*

              [destination]

                 [recipient]
                 file://afd@local/data/out1

           [files]
           out2*

              [destination]

                 [recipient]
                 file://afd@local/data/out2

           [files]
           out3*

              [destination]

                 [recipient]
                 sftp://afd@local/data/out3

           [files]
           out4*

              [destination]

                 [recipient]
                 ftp://ftponly:secret@local/data/out4

     Selecting files from a directory

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           out1*

              [destination]

                 [recipient]
                 file://afd@local/data/out1

           [files]
           !out1*
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out2
                 sftp://afd@local/data/out3
                 ftp://ftponly:secret@local/data/out4

     Source directory on a remote system

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ftp://ftp.dwd.de/pub/afd

           [dir options]
           do not remove
           store retrieve list
           time */10 * * * *

           [files]
           Changelog
           afd-*.bz2
           patch-*.bz2

              [destination]

                 [recipient]
                 file://afd@local/data/afd


   - Renaming files locally and/or at target

        Rename locally, simple

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out

                 [options]
                 rename local_simple

        $AFD_WORK_DIR/etc/rename-rule

        [local_simple]
        * XYZ

        Rename locally, complicated

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out

                 [options]
                 rename local_complicated

        $AFD_WORK_DIR/etc/rename-rule

        [local_complicated]
        *_*_*_???  %?3%?2%?1_%*3_%*2_%*1


        Rename at target

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/out

                 [options]
                 trans_rename tree
                 create target dir

        $AFD_WORK_DIR/etc/rename-rule

        [tree]
        *_*_*_*    */*/*/*


   - Sending files via mail

     Always remember mail is not reliable and not save! Also note that by
     default AFD will try to send its mail to localhost. If you do not
     want this you can use the server=<mail server> parameter in the
     recipient string. Even better is to use the DEFAULT_SMTP_SERVER
     parameter in $AFD_WORK_DIR/etc/AFD_CONFIG file. 

     Simple example sending a picture via mail.

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in/pictures

           [files]
           *.jpg

              [destination]

                 [recipient]
                 mailto://Holger.Kiehl@dwd.de

                 [options]
                 attach file
                 subject "Picture %s"

     Complex example sending different files to different destinations
     with just one entry.

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in/mail

           [files]
           *.txt

              [destination]

                 [recipient]
                 mailto://mail_out

                 [options]
                 subject "%s" mail_subject
                 file name is target mail_target
                 attach file mail_filename

        $AFD_WORK_DIR/etc/rename-rule

        [mail_subject]
        *\ *\ *       %*3

        [mail_target]
        *\ *\ *       %*2

        [mail_filename]
        *\ *          %*1

     A file with the name "afd.c Holger.Kiehl@dwd.de This is the AFD code."
     will be send to Holger.Kiehl@dwd.de the attached filename will be
     afd.c and the subject of the mail will be "This is the AFD code.".


   - The exec option

     This allows you to execute any command before AFD transmits the
     data. If one wants to resize the size of an image to a certain
     size one can use the following:

        $AFD_WORK_DIR/etc/DIR_CONFIG

        [directory]
        ~afd/data/in

           [files]
           *

              [destination]

                 [recipient]
                 file://afd@local/data/png

                 [options]
                 exec convert -geometry 848x480! %s resized_%s

     The %s is the place holder for file name. If AFD picked up more then
     one file it executes the command for each file in a loop. The %s place
     holder can only be used 10 times for each exec line.

     If the user wants to put all file names at once on the exec command
     line, just use the * as shown below:

                 [options]
                 exec tar --remove-files -cf all_files.tar *

     It is possible to path arguments to the exec command:

           -d Deletes the original file after executing the command
              regardless if the command was successful or not.

           -l This sets a lock so that only one process can be executed
              at one time for each file.

           -t <time in second> If after the given timeout the execution
                               has not finished the process will be killed.

     For more information see:

        http://www.dwd.de/AFD/html-en/dir_config.html#exec

     One can also execute a command after the file is distributed, this
     must be done via the pexec option.


   - File Locking

     When one sends data to another host it is important to understand
     that one must use some form of locking. If you do not consider this
     you will loose data! See the following diagram:

                   Sender                   Recipient

                 Application <----------> Application
                     |                        |
                    FTP <------------------> FTP
                     |                        |
                    TCP <------------------> TCP
                     |                        |
                    IP  <------------------> IP
                     |                        |
        -------------+------------------------+----------------

     Each level must communicate with each other. That also goes for
     the last level, your application. Most common way to do this is
     via renaming files.

     AFD supports all forms of locking, here follow just a view:

            .*       *           lock DOT
            tmp.*    *           lock tmp.
            *_tmp    *           plock _tmp


   - Age limit

     If one does not reach a partner, for what ever reason (network not
     working, system down), it does not make sense to send data that is
     to old. For this reason it is possible to set the following:

                  [options]
                  age-limit 3600

     The value here is in seconds. So in the above example if the
     age of the file is older then 1 hour it will be deleted.


   - Working with priorities

     To give some files preference over others because they are more
     important one can do this via the option priority and the priority
     number. 0 is the highest priority and 9 is the lowest. If no
     priority is specified the default is 9.

                 [options]
                 priority 3

     Note that priorities within AFD have an aging effect. Each time
     AFD fails to transit a file for whatever reason it's priority
     decreases. The reason for this is that a single file does not
     block the transfer to a host because for example the file already
     exists and one may now overwrite files on this host. If one does
     not want this behavior one can disable this via the edit_hc
     dialog by setting "No aging jobs".


   - Configuring checks for duplicates

     There are two ways to check for duplicate files, one is on input
     and is set via the option dup_check under [dir options]. And the
     other is on output either for a single host (via HOST_CONFIG) or
     for a single job by setting dup_check under [options].

     There are several ways one can do the check itself. The most common
     is on the file name. Doing it on the content of the file is also
     possible but takes longer and consumes more computer resources.
     The check itself is just a simple CRC32 check-sum.

     If a duplicate is detected there are several things one can, the
     most common is to delete the file.


   - Exercise

     In this exercise we all need to work together. We have four virtual
     systems (ubuntu, redhat, fedora, suse). Each user must configure his
     AFD to send all data coming into the directory ~/data/wmo to the
     next 'higher' user.

     That is usr1@ubuntu sends to usr2@ubuntu. And usr2 sends to
     usr3@ubuntu. The last ubuntu user then sends to usr1@redhat. Aim is
     to create a big loop so the last user on suse must send the file to
     usr1@ubuntu.

     The DIR_CONFIG entry could look as follows:

        [directory]
        ~/data/wmo

           [files]
           *

              [destination]

                 [recipient]
                 ftp://usr2:afdusr2@ubuntu/data/wmo

     Once configured, each user issues the following command:

          touch ~/data/wmo/<your user name>@<your hostname>

     So usr1 on ubuntu issues the following command:

          touch ~/data/wmo/usr1@ubuntu