zcat man page


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.

zcat — expand and concatenate data


zcat [file...]


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

Input files shall be compressed files that are in the format produced by the compress utility.

Environment Variables

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.1‐2008, 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.

Asynchronous Events



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.

Exit Status

The following exit values shall be returned:

Successful completion.
An error occurred.

Consequences of Errors


The following sections are informative.

See Also

compress, uncompress

The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment Variables


2013 IEEE/The Open Group POSIX Programmer's Manual