NAME

       dact - compress or expand a file or stream

SYNOPSIS

       dact  [  -dsfcvlniCHOShVNa  ] [-b size] [-e algo] [-m file] [-o file] [-u url] [-p url] [-M command]
       [-D desc] [-I algo] [-U file] [-E cipher] [file ...]

DESCRIPTION

       DACT reduces input files by attempting to compress each block of  the  file  with  several
       different algorithms and selects the best one for each block.

OPTIONS

       -d     Decompress  the  file (or stdin, if no file is given), removing the extension if it
              has a valid one.

       -s     Display statistics about the file, such as: Magic number of file, DACT version file
              was  compressed  with,  Block  size  used  to  compress file, Compressed file size,
              Original file's  size,  Compression  ratio  (uncompressed  to  compressed),  File's
              original name, CRCs (if available).

       -f     Force  bad  and unsafe things to happen.  Can be combined to make even worse things
              happen.  One `-f' allows overwriting of existing files,  two  `-f'  allows  you  to
              ignore bad magic and CRC check fails.

       -c     Send  output to stdout, this will allow you to force DACT to send compressed output
              to a terminal or result of compressing a file to a pipe.

       -v     Increase verbosity, can be combined to increase verbosity a lot.   Currently,  only
              up to 3 makes sense.  One `-v' displays a bar graph.  Two `-v' displays a bar graph
              and block information.  Three `-v' displays a bar graph  and  detailed  compression
              statistics per block.

       -l     List compression algorithms available.

       -n     Toggle  use  of  CRCs.   This  option  is  especially useful when combined with the
              network capabilities of DACT.  It allows you to create a compressed file with  only
              the  header pointing to a web page that contains the real DACT file (which normally
              has its CRCs checked against the compressed  header  to  ensure  they're  the  same
              file), with this option the files do not have to be from the same source (i.e., you
              can have an updated copy automatically extend itself.)

       -i     Read input from standard input instead of /dev/tty.  This  is  used  to  read  user
              supplied information like encryption keys and passwords from standard input instead
              of the more appropriate method of opening "/dev/tty."

       -C     Complain when compression errors occur.  When a block is selected, it is tested  to
              ensure  that  it  decompresses  back  to  the  original  source.   If it fails, the
              algorithm is not used, with this option you are informed of the failure.

       -H     Write only header (no data).  This option is useful for distributing archives  that
              need only reside on the internet someplace.

       -O     Toggle  writing  original file name in the DACT header. This has no real use that I
              know of.

       -S     Use speed-size as a metric rather than size.  This is not  implemented  yet.   This
              will   make   DACT   create  an  optimized  compressed  file,  balancing  speed  of
              decompression with size.

       -h     Give usage synopsis.

       -V     Display DACT version.

       -N     Upgrade DACT.  This option will fetch the latest binary from the internet and place
              it  in  $HOME/.dact/  as dact.bin.  If you have `binary_check on' in your dact.conf
              file, DACT will check for this file and use it.  If you have Debian and  run  `dact
              -N'   as root the Debian upgrade procedure will upgrade your entire system.

       -a     DACT  modules.   This  option  will  fetch the latest modules from the internet and
              place them in $HOME/.dact/ in a subdirectory corresponding to your Operating System
              and CPU Architecture.

       -b size
              Use  the  specified  block  size  to  compress the file.  The size parameters is in
              bytes.

       -e num Exclude an algorithm from being used.  This option  is  useful  if  you  know  your
              target  will  not  be  able  to  decompress  a certain algorithm (you can get their
              numbers from the `-l' option.)

       -m file
              Load another config file.  This option will attempt to load the specified  file  in
              addition  to  the  normal  files,  the  options  in  this file will supersede other
              options.

       -o file
              Alternate output.  This option sends output to a file instead of  INFILE.dct.   The
              file can also be a URL or '-' for standard out.

       -u url This  option  will  encode an URL in the compressed file's header, this URL will be
              tried (and CRCs checked) before attempting to decompress the  data  in  the  actual
              file.

       -p url URLs  in  DACT can have variables in them that will be expanded when network access
              is required, this allows you to test the  results  of  that  extrapolation  easily.
              Variables and their values are:
                  @@OSNM@@        OS Name (linux, freebsd, sunos, etc)
                  @@OSVR@@        OS version (2.2.x, 4.2, 5.8, etc)
                  @@OSVS@@        OS version (short) (2.2, 4.2, 5.8, etc)
                  @@ARCH@@        Arch (i386, sparc64, sun4u, sun4m, etc)
                  @@DIST@@        If OSNM=Linux, distribution of Linux.
                  @@FILE@@        Name of compressed file.
                  @@DTVR@@        Version of DACT (maj.min.rev)
                  @@DTVS@@        Version of DACT (short) (maj.min)
                  @@PASS@@        Prompt for Password
                  @@USER@@        Prompt for Username
                  @@ATSN@@        Put an `@'
                example:
                  dact                                                                         -p
              http://www.rkeene.org/devel/dact/precompiled/dact-@@OSNM@@-@@OSVS@@-@@ARCH@@.bin
                  dact: http://www.rkeene.org/devel/dact/precompiled/dact-linux-2.4-i586.bin

       -M command
              This option executes a  command  from  the  command  line  as  if  it  appeared  in
              "dact.conf".

       -D desc
              Encode the description specified into the header of the compressed file.

       -I num Use only 1 algorithm (and uncompressed as a fall-back), useful if you want to limit
              yourself to a certain type of compression.

       -U file
              Encode the specified file into the header of the compressed file.  This  file  will
              be  searched  (line-by-line) for a working URL to download compressed content from.
              See also `-u.'

       -E cipher
              Enable encryption using the specified algorithm, different algorithms use different
              authentication methods.

FILES

         $HOME/.dact/
         $HOME/.dact/dact.conf
         /etc/dact.conf

SEE ALSO

       gzip(1), bzip2(1), mcrypt(3)

AUTHOR

       Roy Keene <dact@rkeene.org>

                                                                                          DACT(1)