# uname

## 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.
    


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