zcat man page on SmartOS

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COMPRESS(1)							   COMPRESS(1)

       compress,  uncompress,  zcat  -	compress,  uncompress files or display
       expanded files

       compress [-fv/] [-b bits] [file]...

       compress -c [-fv] [-b bits] [file]

       uncompress [-fv] [-c | -/] [file]...

       zcat [file]...

       The compress utility attempts to reduce the size of the named files  by
       using  adaptive	Lempel-Ziv  coding.  Except  when the output is to the
       standard output, each file is replaced by one with  the	extension  .Z,
       while  keeping  the same ownership modes, change times and modification
       times, ACLs, and extended attributes. The compress utility also attempt
       to  set	the  owner and group of file.z to the owner and group of file,
       but does not fail if this cannot be done. If appending the  .Z  to  the
       file  pathname  would  make the pathname exceed 1023 bytes, the command
       fails. If no files are specified, the standard input is	compressed  to
       the standard output.

       The  amount  of	compression obtained depends on the size of the input,
       the number of bits per code, and the distribution of common substrings.
       Typically,  text	 such  as source code or English is reduced by 50−60%.
       Compression is generally much better than that achieved by Huffman cod‐
       ing  (as	 used  in pack(1)) and it takes less time to compute. The bits
       parameter specified during compression is encoded within the compressed
       file, along with a magic number to ensure that neither decompression of
       random data  nor	 recompression	of  compressed	data  is  subsequently

       The  uncompress	utility	 restores  files to their original state after
       they have been compressed using the compress utility. If no  files  are
       specified, the standard input is uncompressed to the standard output.

       This  utility  supports the uncompressing of any files produced by com‐
       press. For files produced by compress on other systems, uncompress sup‐
       ports 9- to 16-bit compression (see -b).

       The  zcat  utility  writes  to standard output the uncompressed form of
       files that have been compressed using compress. It is the equivalent of
       uncompress-c. Input files are not affected.

       The following options are supported:

       -b bits
		  Sets	the  upper limit (in bits) for common substring codes.
		  bits must be between 9 and 16 (16 is the default).  Lowering
		  the number of bits result in larger, less compressed files.

		  Writes  to  the standard output; no files are changed and no
		  .Z files are created. The behavior of zcat is	 identical  to
		  that of `uncompress -c'.

		  When	compressing,  forces  compression  of file, even if it
		  does not actually reduce the size of the  file,  or  if  the
		  corresponding file.Z file already exists.

		  If  the  -f  option is not specified, and the process is not
		  running in the background,  prompts  to  verify  whether  an
		  existing  file  should  be  overwritten.  If the response is
		  affirmative, the existing file is overwritten.  When	uncom‐
		  pressing,  does  not prompt for overwriting files. If the -f
		  option is not specified, and the process is not  running  in
		  the  background,  prompts to verify whether an existing file
		  should be overwritten. If the standard input is not a termi‐
		  nal  and -f is not specified, writes a diagnostic message to
		  standard error and exits with a status greater than 0.

		  Verbose. Writes to standard error  messages  concerning  the
		  percentage reduction or expansion of each file.

		  When	compressing or decompressing, copies any extended sys‐
		  tem attributes associated with the source file to the target
		  file	and  copies  any extended system attributes associated
		  with extended attributes of the source file  to  the	corre‐
		  sponding  extended  attributes  associated  with  the target
		  file. If any extended system attributes  cannot  be  copied,
		  the  original	 file  is retained, a diagnostic is written to
		  stderr, and the final exit status is non-zero.

       The following operand is supported:

	       A path name of a file to	 be  compressed	 by  compress,	uncom‐
	       pressed by uncompress, or whose uncompressed form is written to
	       standard out by zcat. If file is −, or if no file is specified,
	       the standard input is used.

       See  largefile(5)  for  the  description	 of  the behavior of compress,
       uncompress, and zcat when encountering files greater than or equal to 2
       Gbyte ( 2^31 bytes).

       See  environ(5) for descriptions of the following environment variables
       that affect the execution of  compress,	uncompress,  and  zcat:	 LANG,

       Affirmative  responses are processed using the extended regular expres‐
       sion defined for the yesexpr keyword in the LC_MESSAGES category of the
       user's  locale. The locale specified in the LC_COLLATE category defines
       the behavior of ranges, equivalence classes, and	 multi-character  col‐
       lating  elements used in the expression defined for yesexpr. The locale
       specified in LC_CTYPE  determines  the  locale  for  interpretation  of
       sequences of bytes of text data a characters, the behavior of character
       classes used in the expression defined for the yesexpr. See locale(5).

       The following error values are returned:

	     Successful completion.

	     An error occurred.

	     One or more files were not compressed  because  they  would  have
	     increased in size (and the -f option was not specified).

	     An error occurred.

       See attributes(5) for descriptions of the following attributes:

       │CSI		    │ Enabled		│
       │Interface Stability │ Committed		│
       │Standard	    │ See standards(5). │

       ln(1),  pack(1), fgetattr(3C), fsetattr(3C), attributes(5), environ(5),
       largefile(5), locale(5), standards(5)

       Usage: compress [-fv/] [-b bits] [file... ]
       compress c [-fv] [-b bits] [file... ]

	   Invalid options were specified on the command line.

       Usage: uncompress [-fv] [-c | -/] [file]...

	   Invalid options were specified on the command line.

       Missing maxbits

	   Maxbits must follow -b, or invalid maxbits, not a numeric value.

       file: not in compressed format

	   The file specified to uncompress has not been compressed.

       file: compressed with xxbits, can only handle yybits

	   file was compressed by a program that could	deal  with  more  bits
	   than	 the  compress	code on this machine. Recompress the file with
	   smaller bits.

       file: already has .Z suffix -- no change

	   The file is assumed to be already compressed. Rename the  file  and
	   try again.

       file: already exists; do you wish to overwrite (y or n)?

	   Respond y if you want the output file to be replaced; n if not.

       uncompress: corrupt input

	   A  SIGSEGV  violation  was  detected,  which usually means that the
	   input file is corrupted.


	   Percentage of the input saved by compression.  (Relevant  only  for

       - - not a regular file: unchanged

	   When	 the  input file is not a regular file, (such as a directory),
	   it is left unaltered.

       - - has xx other links: unchanged

	   The input file has links; it is left unchanged. See ln(1) for  more

       - - file unchanged

	   No  savings	are  achieved by compression. The input remains uncom‐

       - -filename too long to tack on .Z

	   The path name is too long to append the .Z suffix.

       - -cannot preserve extended attributes. file unchanged

	   Extended system attributes could not be copied.

       Although compressed files are compatible between	 machines  with	 large
       memory,	-b 12 should be used for file transfer to architectures with a
       small process data space (64KB or less).

       compress should be more flexible about the existence of the .Z suffix.

				 Mar 13, 2008			   COMPRESS(1)

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