pack(1) 						      General Commands Manual							   pack(1)

NAME

       pack, pcat, unpack - Compresses and expands files

SYNOPSIS

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

       unpack file[.z]...

       pcat file[.z]...

STANDARDS

       Interfaces documented on this reference page conform to industry standards 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.

OPTIONS

       Displays  statistics  about  the input files. The statistics are calculated 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.

									  Note

       These options are applicable to the pack command only.

OPERANDS

       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 command 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.

DESCRIPTION

   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
       packed.

       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 con-
       ditions: 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 during 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 specified, 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 created.

NOTES

       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.

EXIT STATUS

       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.

EXAMPLES

       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 per-
	      cent decrease in size for each file.  To display statistics about the amount of compression done, enter: pack  -	chap1  -  chap2

	      This compresses the files chap1 and chap2 and displays statistics about chap1, but not about chap2. The first - (dash) turns on  the
	      statistic display, and the second turns it off.  To display 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 command
	      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  chap2

	      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.

ENVIRONMENT VARIABLES

       The following environment variables affect the execution of pack, pcat, and unpack: Provides a default value for  the  internationalization
       variables  that are unset or null. If LANG is unset or null, the corresponding value from the default locale is used.  If any of the inter-
       nationalization 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 internationalization 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.

SEE ALSO

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

       Standards:  standards(5)

																	   pack(1)