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zidrav(1)                                                            zidrav(1)

NAME
       zidrav - detect and repair corruption in transfered files

SYNOPSIS
       zidrav [-b bs] [-o CDT] corrupted file
       zidrav -p [-i CDT] [-o CDP] original file
       zidrav -a [-i CDP] corrupted file

DESCRIPTION
       zidrav is a file corruption detection and repair program.  It's
       designed to provide a way to fix file damage without having to
       redownload the entire (potentially large) file over a (potentially
       slow) connection.

       There are 3 steps to using zidrav (in the order of the SYNOPSIS
       commands):

              1.  Create a checksum file of the corrupted file.

              2.  Using the checksum file, create a patch file from the
              original file.

              3.  Apply the patch file to the corrupted file.

       At each of the steps, the checksum or patch file has to be in the same
       directory as the corrupted or original file, depending on which step
       you're on, unless otherwise specified with -i.

OPTIONS
       -a     Apply the patch file to the corrupted file in order to fix it.

       -b     Set the blocksize.  The default blocksize it 16384.

       -h     Show usage summary and exit.

       -i     Specify the input filename of the checksum (CDT) or patch (CDP)
              files.  You have to use this flag when the basename of the
              checksum or patch files doesn't match the name of the original
              file.

       -o     Specify an output filename for the checksum (CDT) or patch (CDP)
              files.  By default, the name of original file is used as the
              basename for these files.

       -p     Build the patch file from the original file.

       -V     Display version information and exit.

EXAMPLE
       In this example, let's assume you've downloaded a large file named
       freebsd4.8.iso from a remote ftp which you have shell access to.  The
       file was corrupted during transfer and you need to use zidrav to fix
       the file.

       First, build a checksum file from the corrupted file on your machine:

              zidrav freebsd4.8.iso

       This creates a checksum file named freebsd.4.8.iso.cdt.

       Next, transfer the checksum file to the remote ftp computer in the same
       directory as the original file.  From that directory, type:

              zidrav -p freebsd.4.8.iso

       This creates a patch file named freebsd.4.8.iso.cdp.

       Last, transfer the patch file back to your computer, in the same
       directory as the corrupted file.  From that directory, type:

              zidrav -a freebsd.4.8.iso

       This will apply the patch and fix the corrupted file.

BUGS
       The corrupted file has to be equal in size as the original file.  This
       makes it so you can't fix partially downloaded files until they're
       padded.

AUTHOR
       zidrav is written by Zorba <zorbathut@uswest.net>.  Unix port was done
       by Piotr Krukowiecki {piotr at krukowiecki dot net}.  This manpage by
       Cosmin Stroe <cstroe1@uic.edu>.

                                 July 14, 2003                       zidrav(1)