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)