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 .