uname(1p) — Linux manual page
UNAME(1P) POSIX Programmer's Manual UNAME(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
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.1‐2017, the symbols written shall be
those supported by the uname() function as defined in the System
Interfaces volume of POSIX.1‐2017.
OPTIONS
The uname utility shall conform to the Base Definitions volume of
POSIX.1‐2017, 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.1‐2017, 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
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.1‐2017 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.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, uname(3p)
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 .