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.
The zcat utility shall write to standard output the uncompressed form of files that have been compressed using the compress utility. It is the equivalent of uncompress -c. Input files are not affected.
The following operand shall be supported:
The pathname of a file previously processed by the compress utility. If file already has the .Z suffix specified, it is used as submitted. Otherwise, the .Z suffix is appended to the filename prior to processing.
The standard input shall be used only if no file operands are specified, or if a file operand is '-'.
Input files shall be compressed files that are in the format produced by the compress utility.
The following environment variables shall affect the execution of zcat:
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.)
If set to a non-empty string value, override the values of all the other internationalization variables.
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).
Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
Determine the location of message catalogs for the processing of LC_MESSAGES.
The compressed files given as input shall be written on standard output in their uncompressed form.
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
An error occurred.
Consequences of Errors
The following sections are informative.
The Base Definitions volume of POSIX.1-2017, Chapter 8, Environment Variables
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 .
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