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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
uname — return system name
SYNOPSIS
uname [−amnrsv]
DESCRIPTION
By default, the uname utility shall write the operating system name to standard output.
When options are specified, symbols representing one or more system characteristics shall
be written to the standard output. The format and contents of the symbols are
implementation-defined. On systems conforming to the System Interfaces volume of
POSIX.1‐2008, the symbols written shall be those supported by the uname() function as
defined in the System Interfaces volume of POSIX.1‐2008.
OPTIONS
The uname utility shall conform to the Base Definitions volume of POSIX.1‐2008, Section
12.2, Utility Syntax Guidelines.
The following options shall be supported:
−a Behave as though all of the options −mnrsv were specified.
−m Write the name of the hardware type on which the system is running to standard
output.
−n Write the name of this node within an implementation-defined communications
network.
−r Write the current release level of the operating system implementation.
−s Write the name of the implementation of the operating system.
−v Write the current version level of this release of the operating system
implementation.
If no options are specified, the uname utility shall write the operating system name, as
if the −s option had been specified.
OPERANDS
None.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of uname:
LANG 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.)
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
By default, the output shall be a single line of the following form:
"%s\n", <sysname>
If the −a option is specified, the output shall be a single line of the following form:
"%s %s %s %s %s\n", <sysname>, <nodename>, <release>,
<version>, <machine>
Additional implementation-defined symbols may be written; all such symbols shall be
written at the end of the line of output before the <newline>.
If options are specified to select different combinations of the symbols, only those
symbols shall be written, in the order shown above for the −a option. If a symbol is not
selected for writing, its corresponding trailing <blank> characters also shall not be
written.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 The requested information was successfully written.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
Note that any of the symbols could include embedded <space> characters, which may affect
parsing algorithms if multiple options are selected for output.
The node name is typically a name that the system uses to identify itself for inter-system
communication addressing.
EXAMPLES
The following command:
uname −sr
writes the operating system name and release level, separated by one or more <blank>
characters.
RATIONALE
It was suggested that this utility cannot be used portably since the format of the symbols
is implementation-defined. The POSIX.1 working group could not achieve consensus on
defining these formats in the underlying uname() function, and there was no expectation
that this volume of POSIX.1‐2008 would be any more successful. Some applications may still
find this historical utility of value. For example, the symbols could be used for system
log entries or for comparison with operator or user input.
FUTURE DIRECTIONS
None.
SEE ALSO
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment Variables, Section
12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2008, uname()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .