trusty (1) uncompress.1posix.gz

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NAME
       uncompress - expand compressed data


SYNOPSIS
       uncompress [-cfv][file...]


DESCRIPTION
       The  uncompress utility shall restore files to their original state after they have been compressed using
       the compress utility.  If no files are specified,  the  standard  input  shall  be  uncompressed  to  the
       standard  output.  If the invoking process has appropriate privileges, the ownership, modes, access time,
       and modification time of the original file shall be preserved.

       This utility shall support the uncompressing of any files produced by the compress utility  on  the  same
       implementation.  For  files  produced  by  compress  on  other  systems,  uncompress supports 9 to 14-bit
       compression (see compress , -b); it is implementation-defined whether values of -b greater  than  14  are
       supported.


OPTIONS
       The  uncompress  utility  shall  conform  to the Base Definitions volume of IEEE Std 1003.1-2001, Section
       12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       -c     Write to standard output; no files are changed.

       -f     Do not prompt for overwriting files. Except when run in the background, if -f  is  not  given  the
              user shall be prompted as to whether an existing file should be overwritten. If the standard input
              is not a terminal and -f is not given, uncompress shall write a  diagnostic  message  to  standard
              error and exit with a status greater than zero.

       -v     Write messages to standard error concerning the expansion of each file.


OPERANDS
       The following operand shall be supported:

       file   A  pathname  of a file. If file already has the .Z suffix specified, it shall be used as the input
              file and the output file shall be named file with the .Z suffix removed.  Otherwise, file shall be
              used  as  the  name  of  the output file and file with the .Z suffix appended shall be used as the
              input file.


STDIN
       The standard input shall be used only if no file operands are specified, or if a file operand is '-' .


INPUT FILES
       Input files shall be in the format produced by the compress utility.


ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of uncompress:

       LANG   Provide a default value for the internationalization variables that are unset or  null.  (See  the
              Base  Definitions  volume of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for
              the  precedence  of  internationalization  variables  used  to  determine  the  values  of  locale
              categories.)

       LC_ALL If  set  to  a  non-empty  string value, override the values of all the other internationalization
              variables.

       LC_CTYPE
              Determine 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).

       LC_MESSAGES
              Determine  the locale that should be used to affect the format and contents of diagnostic messages
              written to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .


ASYNCHRONOUS EVENTS
       Default.


STDOUT
       When there are no file operands or the -c option is specified, the  uncompressed  output  is  written  to
       standard output.


STDERR
       Prompts  shall  be written to the standard error output under the conditions specified in the DESCRIPTION
       and OPTIONS sections.  The prompts shall contain  the  file  pathname,  but  their  format  is  otherwise
       unspecified. Otherwise, the standard error output shall be used only for diagnostic messages.


OUTPUT FILES
       Output files are the same as the respective input files to compress.


EXTENDED DESCRIPTION
       None.


EXIT STATUS
       The following exit values shall be returned:

        0     Successful completion.

       >0     An error occurred.


CONSEQUENCES OF ERRORS
       The input file remains unmodified.

       The following sections are informative.


APPLICATION USAGE
       The  limit  of  14  on the compress -b bits argument is to achieve portability to all systems (within the
       restrictions imposed by the lack of an explicit published file format).  Some  implementations  based  on
       16-bit architectures cannot support 15 or 16-bit uncompression.


EXAMPLES
       None.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       compress , zcat


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group. In the event of any discrepancy between this version and the  original  IEEE  and
       The  Open  Group  Standard,  the  original  IEEE and The Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .