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

COPYRIGHT

       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 .