uname(2)                      System Calls Manual                     uname(2)

NAME
       uname - get name and information about current kernel

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <sys/utsname.h>

       int uname(struct utsname *buf);

DESCRIPTION
       uname() returns system information in the structure pointed to by buf.
       The utsname struct is defined in <sys/utsname.h>:

           struct utsname {
               char sysname[];    /* Operating system name (e.g., "Linux") */
               char nodename[];   /* Name within communications network
                                     to which the node is attached, if any */
               char release[];    /* Operating system release
                                     (e.g., "2.6.28") */
               char version[];    /* Operating system version */
               char machine[];    /* Hardware type identifier */
           #ifdef _GNU_SOURCE
               char domainname[]; /* NIS or YP domain name */
           #endif
           };

       The length of the arrays in a struct utsname is unspecified (see
       NOTES); the fields are terminated by a null byte ('\0').

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and errno is
       set to indicate the error.

ERRORS
       EFAULT buf is not valid.

VERSIONS
       The domainname member (the NIS or YP domain name) is a GNU extension.

       The length of the fields in the struct varies.  Some operating systems
       or libraries use a hardcoded 9 or 33 or 65 or 257.  Other systems use
       SYS_NMLN or _SYS_NMLN or UTSLEN or _UTSNAME_LENGTH.  Clearly, it is a
       bad idea to use any of these constants; just use sizeof(...).  SVr4
       uses 257, "to support Internet hostnames" -- this is the largest value
       likely to be encountered in the wild.

STANDARDS
       POSIX.1-2008.

HISTORY
       POSIX.1-2001, SVr4, 4.4BSD.

   C library/kernel differences
       Over time, increases in the size of the utsname structure have led to
       three successive versions of uname(): sys_olduname() (slot
       __NR_oldolduname), sys_uname() (slot __NR_olduname), and sys_newuname()
       (slot __NR_uname).  The first one used length 9 for all fields; the
       second used 65; the third also uses 65 but adds the domainname field.
       The glibc uname() wrapper function hides these details from
       applications, invoking the most recent version of the system call
       provided by the kernel.

NOTES
       The kernel has the name, release, version, and supported machine type
       built in.  Conversely, the nodename field is configured by the
       administrator to match the network (this is what the BSD historically
       calls the "hostname", and is set via sethostname(2)).  Similarly, the
       domainname field is set via setdomainname(2).

       Part of the utsname information is also accessible via
       /proc/sys/kernel/{ostype, hostname, osrelease, version, domainname}.

SEE ALSO
       uname(1), getdomainname(2), gethostname(2), uts_namespaces(7)

Linux man-pages 6.7               2023-10-31                          uname(2)