arc.doc

汇编大全 中国矿业大学计算机学院 汇编实验5

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          arc - pc archive utility

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          aaaarrrrcccc a|m|u|f|d|x|e|r|p|l|v|t|c [ biswnoq ] [ g_p_a_s_s_w_o_r_d ]
          _a_r_c_h_i_v_e [ _f_i_l_e_n_a_m_e ...]

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          _A_r_c is a general archive and file compression utility, used
          to maintain a compressed archive of files.  An _a_r_c_h_i_v_e is a
          single file that combines many files, reducing storage space
          and allowing multiple files to be handled as one.  _A_r_c uses
          one of several compression methods for each file within the
          _a_r_c_h_i_v_e, based on whichever method yields the smallest
          result.

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          Execute _a_r_c with no arguments for fairly verbose, usable
          instructions.

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          a  add files to archive.  Copies the indicated files to the
             archive.

          m  move files to archive.  Same as 'a' switch except that
             the files are deleted from the directory as they are
             moved to the archive.

          u  update files in archive.  This switch will replace
             archived files when the named file is newer than the
             archived copy.  New files will be added automatically.

          f  freshen files in archive.  Same as 'u' except that new
             files will not be added.

          d  delete files in archive.  The named files are removed
             from the archive.

          x,e
             extract files from archive.  The named files are
             extracted from the archive and created in the current
             directory in an uncompressed state.

          r  run one file with arguments from archive.  Any program
             may be executed directly from the archive.  The
             parameters given after the program name are passed to the
             program without modification.

          p  copy files from archive to standard output.  Useful with
             I/O redirection. A form-feed is appended after each file,
             to ease use with printers.




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          l  list files in archive.  Limited information listing of
             files contained in an archive.  Displays the filename,
             original length, and date last modified.  If the 'n'
             option (see below) is used, only the filename is
             displayed.

          v  verbose listing of files in archive.  Complete
             information listing of files contained in an archive.
             Displays the filename, original length, storage method,
             storage factor (% savings), compressed size, date, time,
             and CRC.

          t  test archive integrity.  Computes CRC values for each
             member of the archive and compares against the previously
             saved value.

          c  convert entry to new packing method.  Convert files
             stored with older methods to newer methods that are more
             efficient. Also useful for files previously archived with
             the 's' option.

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          b  retain backup copy of archive.  Keep the original archive
             file and rename to .BAK.  This switch may be used with
             the following commands:  a, m, u, f, d, c.

          i  suppress image mode.  This switch causes files to be
             treated as text files, and will translate their end-of-
             line sequence. (Unix's '\n' vs. '\r\n' used on many other
             systems.)  The default is to perform no translation when
             compressing or extracting files.  This option makes
             dealing with text files much nicer, though the 'tr'
             command can also be used. ('\r' in makefiles and C source
             code is such a nuisance...)

          s  suppress compression.  This forces new files to be saved
             using Method 2 (no compression).  This switch may be used
             with the following commands:  a, m, u, f, c.

          w  suppress warning messages.  This switch will keep warning
             messages from being displayed which is the default.  Most
             warnings concern the deletion or existence of files with
             the same name.

          n  suppress notes and comments.  This switch will keep
             useful notes from being displayed which is the default.
             Most notes indicate what stage of compression is being
             run (analyze, compaction, storage).

          o  overwrite existing files when extracting.  This switch
             will make existing files silently get overwritten,
             instead of asking for confirmation, which is the default.



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          q  force Squash compression method.  This switch causes the
             Squash compression method to be used, instead of Crunch,
             which is the default.

          g  encrypt/decrypt archive entry.  This is used to encode
             files so that others may not read them.  BE CAREFUL!
             This must be the last parameter in the switches because
             everything following is part of the password.

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          _A_r_c Version 2 differs from version 1 in that archive entries
          are automatically compressed when they are added to the
          archive, making a separate compression step unecessary.  The
          nature of the compression is indicated by the header version
          number placed in each archive entry, as follows:
                   1 = Old style, no compression
                   2 = New style, no compression
                   3 = Compression of repeated characters only
                   4 = Compression of repeated characters plus Huffman SQueezing
                   5 = Lempel-Zev packing of repeated strings (old style)
                   6 = Lempel-Zev packing of repeated strings (new style)
                   7 = Lempel-Zev Williams packing with improved hash function
                   8 = Dynamic Lempel-Zev packing with adaptive reset
                   9 = Squashing

          Type 5, Lempel-Zev packing, was added as of version 4.0

          Type 6 is Lempel-Zev packing where runs of repeated
          characters have been collapsed, and was added as of version
          4.1

          Type 7 is a variation of Lempel-Zev using a different hash
          function which yields speed improvements of 20-25%, and was
          added as of version 4.6

          Type 8 is a different implementation of Lempel-Zev, using a
          variable code size and an adaptive block reset, and was
          added as of version 5.0

          Type 9 is another variation of Lempel-Zev, using a larger
          hash table. This method was developed by Phil Katz, and is
          not supported by the "official" AAAARRRRCCCC programs.

          _A_r_c will look for environment variables named _A_R_C_T_E_M_P or
          _T_M_P_D_I_R, which, if present, indicates the pathname where
          temporary files should be created. This is typically the
          location of a RAMdisk on a microcomputer, "/tmp/" or left
          unset.

          See the included documentation file for more details.

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     AAARRRCCC(((111LLL)))                LLLooocccaaalll (((111222 JJJuuunnn 111999888888)))                AAARRRCCC(((111LLL)))



          _A_r_c has been in use in the CP/M and MSDOS world for many
          years.  Thom Henderson developed the original version, but
          it is important to note that _a_r_c is based on the file
          compression theories developed by Huffman, Welch, Knott,
          Knuth, and many other scientists. This implementation is
          based on version 5.21 of the MSDOS program.

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          _A_r_c behaves just like the PC version of the program; all
          functions of the "usage" display are working.  Full
          compatibility with PC ARC files is maintained, the price for
          which is that _a_r_c doesn't like long filenames, and can only
          archive files with names of up to 12 characters.  It will
          *sometimes* do The Right Thing with them, but I suggest you
          put long-winded filenames in a "shar" before _a_r_cing them.

          There shouldn't be any problems, (hah!) but if you find any,
          please send them to me at:

               [e-mail]      {rutgers, uunet}!umix!hyc


     AAAUUUTTTHHHOOORRRSSS
          Original MSDOS program by Thom Henderson
          COPYRIGHT(C) 1985-87 by System Enhancement Associates; ALL
          RIGHTS RESERVED

          Original Lempel-Zev code derived from compress 4.0.
          Modified to support Squashing by Dan Lanciani
          ([e-mail]) Ported from MSDOS by Howard Chu
          (umix!hyc), with help from John Gilmore (hoptoad!gnu), James
          Turner (daisy!turner) and others.























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