CRC(1)                  AmigaDOS 1.2                  CRC(1)

NAME 
   crc - generate or verify a 16-bit crc for a file 


SYNOPSIS 
   crc [-g|-G|-v|-V] [filename ...] 


REVISION 
   1.000, compiled with Manx 3.4b C compiler. 


DESCRIPTION 
   crc provides a means of verifying two files are the same
   with a relatively high degree of certainty. It does this
   without the neccessity of having a duplicate of the file
   immediately accessible. A 16-bit crc (cyclic redundancy
   check) is calculated for a file's contents. This crc can
   either be saved, or automatically compared to a reference
   crc previously calculated. Decisions can then be made
   according to the code returned. 

   When no options are specified, crc, by default,
   interprets all parameters on the command line as file
   names. For each file name, the file is opened and a CRC
   is calculated. Then the file name and CRC are written to
   the standard output. File names may include wild card
   characters. If an error occurs while processing a file,
   an appropriate message is written to the standard output
   and processing continues with the next file name. 

   OPTIONS 
      If there is only one command line parameter and it
      starts with a '-' (minus) character, it is interpreted
      as an option. If there is more than one command line
      parameter, or one command line parameter and it does
      not start with '-', all command line parameter(s) are
      interpreted as file names. Only one option may be
      specified from the command line. 

      -g Generate option. This causes the standard input to
         be parsed for file names until an end of file
         character is detected. File names may include wild
         card characters(explained later). 

      -G Same as -g option. 

      -v Verify option. This causes the standard input to be
         parsed for file names until an end of file
         character is detected. Wild card characters are
         interpreted literally with no special meaning. For
         each file name parsed, the CRC is computed for the
         file and then compared to the CRC string on the end
         of the line. Any mismatch will cause a return code
         of 10. If an error occurs while processing the
         file, an appropriate error message is written to
         the standard output and the return code is set to
         10. Even though an error is detected, processing is

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CRC(1)                  AmigaDOS 1.2                  CRC(1)

         continued until the end of file character from the
         standard input. The file-names are NOT echoed back
         to the standard output, unless an error occurrs. 

      -V Same as -v, except nothing is sent to the standard
         output. Normally some sort of heading message is
         sent to the standard output. 

      Note that any time an option is specified, the
      standard input will be read until an EOF character
      (control '\', from the Amiga keyboard) is encountered. 

   WILDCARD EXPANSION 
      File names may contain wild card characters. '?'
      matches any single character. '*' matches any number
      of characters. The verify (-v or -V) option won't make
      any substitions. Instead, it interprets '*' and '?'
      literally. 

   ODD CHARACTERS IN FILE NAMES 
      If a file name contains a space, the name must be
      enclosed inside double quotes ("). 

   COMMENT LINES 
      For the -g, -G, -v and -V options, all blank lines and
      comment lines are ignored. A comment line starts with
      the # character and ends with the newline character. 


ERRORS 
   crc sets a return code of 10 if any type of error was
   encountered. A return code of 0 means everything was OK. 


EXAMPLES 
   To generate crc's for files "file1" and "FILE 2" you
   could enter: 
      crc file1 "FILE 2" 

   To generate the crc's again and save them in in a file
   "tmp", enter this: 
      crc >tmp file1 "FILE 2" 

   To verify those two files you might enter: 
      crc <tmp -v 

   To verify those two files again and make a decision based
   on the error code: 
      FAILAT 11 
      crc <tmp -v 
      if ERROR 
         echo "There was an error" ;do this if the crc's don't match
      else 
         echo "Files are OK" ;do this if the crc's are OK 
      endif 

   To generate new crc's for the previous files: 
      crc <tmp -g 

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CRC(1)                  AmigaDOS 1.2                  CRC(1)


   To generate crc's for all files in the current directory
   with names containing the letter "A": 
      crc *A* 


AUTHOR 
   Don Kindred 


BUGS 
   No major bugs have been reported. If you find any bugs or
   would like to hire a good C programmer, fell free to drop
   me a line: 
      Don Kindred 
      5430 S. Keystone Ave. 
      Indpls., IN 46227 










































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