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pack(1)								       pack(1)

       pack, pcat, unpack - Compresses and expands files

       pack [-f] [-] file[.z]...

       unpack file[.z]...

       pcat file[.z]...

       Interfaces  documented on this reference page conform to industry stan‐
       dards as follows:

       pack: XCU5.0

       pcat:  XCU5.0

       unpack:	XCU5.0

       Refer to the standards(5) reference page	 for  more  information	 about
       industry standards and associated tags.

       Displays	 statistics  about  the input files. The statistics are calcu‐
       lated from a Huffman minimum redundancy code tree built on  a  byte-by-
       byte  basis.   Repeating	 the - (dash) on the command line toggles this
       function.  Forces compaction of input files.


       These options are applicable to the pack command only.

       A pathname of a file to be compressed or uncompressed.

	      If the suffix is included on the pack command, pack searches for
	      files  without  that suffix.  If the suffix is not included, the
	      files created have the original name with appended.

	      If the suffix is included on a pcat or unpack command, the  com‐
	      mand  processes  files  with  that  name.	  If the suffix is not
	      included, the command appends to the file name.

	      Files created by the unpack command will not have the suffix.

   The pack command
       The pack command stores the specified file in a compressed  form.   The
       input  file  is	replaced by a packed file with a name derived from the
       original file name (file.z), with the ownership, modes, access time and
       modification  time  of  the  original  file  preserved, if the invoking
       process has appropriate privileges.

       Directories cannot be compressed.

       If pack cannot create a smaller file, it stops processing  and  reports
       that  it	 is  unable  to	 save space, unless you specify the -f option.
       (The -f option forces packing to occur even if the files cannot benefit
       from  packing.)	 A  failure to save space generally happens with small
       files or files with uniform character distribution.

       The amount of space saved depends on the size of the input file and the
       character  frequency  distribution.   Because a decoding tree forms the
       first part of each file, you will generally not be able to  save	 space
       with  files  smaller  than  three  blocks.   Typically,	text files are
       reduced 25 to 40 percent.

       Object files, which use a larger character set and have a more  uniform
       distribution  of	 characters,  show  only  a  10 percent reduction when

       The exit value of the pack command is the number of files that it could
       not  pack.   Packing  is not done under any one of the following condi‐
       tions: The file is already packed.  The file has links.	The file is  a
       directory.   The file cannot be opened.	No storage blocks are saved by
       packing. This is overridden by the -f option.   A  file	called	file.z
       already	exists.	 The file cannot be created.  An I/O error occurs dur‐
       ing processing.	The file is empty.

   The pcat command
       The pcat command reads the specified files, unpacks  them,  and	writes
       them to standard output.

       The  exit value of pcat is the number of files it was unable to unpack.
       A file cannot be unpacked if any one of the following occurs: The  file
       cannot  be  opened.   The file is not a packed file.  [Tru64 UNIX]  The
       file name (exclusive of the has more than 12 bytes and it resides on  a
       System V file system.

   The unpack command
       The unpack command expands files created by pack.  For each file speci‐
       fied, unpack searches for a file called file.z.	 If  this  file	 is  a
       packed  file,  unpack  replaces it by its expanded version.  The unpack
       command names the new file name by removing the suffix from file.   The
       new  file has the same access modes, access and modification dates, and
       owner as the original packed file.

       The exit value is the number of files the unpack command was unable  to
       unpack.	 A file cannot be unpacked if any one of the following occurs:
       The file cannot be opened.  The file is not a packed file.  A file with
       the  unpacked  file  name  already exists.  The unpacked file cannot be

       The pack, pcat and unpack utilities are marked LEGACY in XCU  Issue  5.
       Both pcat and unpack operate only on files ending in you specify a file
       name that does not end in pcat and unpack add the suffix and search the
       directory  for  a file name with that suffix.  [Tru64 UNIX]  The unpack
       command writes a warning to standard output if the file it is unpacking
       has links.  The new unpacked file has a different inode than the packed
       file from which it was created.	However, any other files linked to the
       packed  file's original inode still exist and are still packed.	[Tru64
       UNIX]  If pack is used on files residing on a System V file system, the
       file  names  must  contain no more than 12 bytes to allow space for the
       added extension.	 [Tru64 UNIX]  If you try to use pack on a very	 small
       file, you might receive the following message: pack filename: No saving
       -- file unchanged The pack, pcat, and unpack commands are marked to  be
       withdrawn  from	the XPG4-UNIX standard.	 The compress, uncompress, and
       zcat commands should be used instead.

       The following exit values are returned:

   The pack command
       Successful completion.  [Tru64 UNIX]  The number of  files  that	 could
       not be packed.

   The pcat command
       Successful  completion.	 [Tru64	 UNIX]	The number of files that could
       not be unpacked.

   The unpack command
       Successful completion.  [Tru64 UNIX]  The number of  files  that	 could
       not be unpacked.

       To compress files, enter: pack chap1 chap2

	      This  compresses	the files chap1 and chap2, replacing them with
	      files named chap1.z and chap2.z.	The pack command displays  the
	      percent  decrease	 in size for each file.	 To display statistics
	      about the amount of compression done, enter: pack	 -   chap1   -

	      This  compresses	the files chap1 and chap2 and displays statis‐
	      tics about chap1, but not about chap2. The first - (dash)	 turns
	      on  the statistic display, and the second turns it off.  To dis‐
	      play compressed files, enter: pcat  chap1.z  chap2 |  more

	      This displays the compressed files chap1.z and  chap2.z  on  the
	      screen in expanded form, a page at a time (more).	 The pcat com‐
	      mand added the to the end of  chap2,  even  though  it  was  not
	      entered.	 To  use  a compressed file without expanding the copy
	      stored on disk, enter: pcat chap1.z  |  grep  'Greece'

	      This pipes the contents of chap1.z in its expanded form  to  the
	      grep  command.   To  unpack packed files, enter: unpack  chap1.z

	      This expands the packed files  chap1.z  and  chap2.z,  replacing
	      them  with files named chap1 and chap2. You can give unpack file
	      names either with or without the suffix.

       The following environment variables affect the execution of pack, pcat,
       and unpack: Provides a default value for the internationalization vari‐
       ables that are unset or null. If LANG is unset or null, the correspond‐
       ing  value from the default locale is used.  If any of the internation‐
       alization variables contain an invalid setting, the utility behaves  as
       if  none	 of  the  variables  had  been defined.	 If set to a non-empty
       string value, overrides the values of all the  other  internationaliza‐
       tion  variables.	  Determines  the  locale  for	the  interpretation of
       sequences of bytes of text data as characters (for example, single-byte
       as  opposed  to	multi-byte  characters	in arguments).	Determines the
       locale for the format and contents of diagnostic	 messages  written  to
       standard	 error.	 Determines the location of message catalogues for the
       processing of LC_MESSAGES.

       Commands:  cat(1), compress(1), uncompress(1), zcat(1)

       Standards:  standards(5)


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