UNCOMPRESS(1P)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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 POSIX.1-2017, Section 12.2, Utility Syntax Guidelines, except that Guideline 1 does apply since the utility name has ten letters.

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 POSIX.1-2017, 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

The Base Definitions volume of POSIX.1-2017, Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .