UNAME(P) POSIX Programmer's Manual UNAME(P)
uname - return system name
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 implementa-
tion-defined. On systems conforming to the System Interfaces volume of
IEEE Std 1003.1-2001, the symbols written shall be those supported by the uname() function
as defined in the System Interfaces volume of IEEE Std 1003.1-2001.
The uname utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001,
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 out-
-n Write the name of this node within an implementation-defined communications net-
-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 implementa-
If no options are specified, the uname utility shall write the operating system name, as
if the -s option had been specified.
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 IEEE Std 1003.1-2001, Section 8.2, Inter-
nationalization 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 interna-
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 argu-
Determine the locale that should be used to affect the format and contents of diag-
nostic messages written to standard error.
Determine the location of message catalogs for the processing of LC_MESSAGES .
By default, the output shall be a single line of the following form:
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>,
Additional implementation-defined symbols may be written; all such symbols shall be writ-
ten at the end of the line of output before the <newline>.
If options are specified to select different combinations of the symbols, only those sym-
bols shall be written, in the order shown above for the -a option. If a symbol is not
selected for writing, its corresponding trailing <blank>s also shall not be written.
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
0 The requested information was successfully written.
>0 An error occurred.
CONSEQUENCES OF ERRORS
The following sections are informative.
Note that any of the symbols could include embedded <space>s, 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
The following command:
writes the operating system name and release level, separated by one or more <blank>s.
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 defin-
ing these formats in the underlying uname() function, and there was no expectation that
this volume of IEEE Std 1003.1-2001 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.
The System Interfaces volume of IEEE Std 1003.1-2001, uname()
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 UNAME(P)