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uname

print system information

uname.1.man
uname.2.man

1. uname.1.man

Manpage of UNAME

UNAME

Section: User Commands (1)
Updated: January 2008
Index Return to Main Contents

NAME

uname - print system information

SYNOPSIS

uname [OPTION]...

DESCRIPTION

Print certain system information. With no OPTION, same as -s.

-a, --all: print all information, in the following order, except omit -p and -i if unknown:
-s, --kernel-name: print the kernel name
-n, --nodename: print the network node hostname
-r, --kernel-release: print the kernel release
-v, --kernel-version: print the kernel version
-m, --machine: print the machine hardware name
-p, --processor: print the processor type or "unknown"
-i, --hardware-platform: print the hardware platform or "unknown"
-o, --operating-system: print the operating system
--help: display this help and exit
--version: output version information and exit

AUTHOR

Written by David MacKenzie.

REPORTING BUGS

Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

Copyright © 2008 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl>
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

This document was created by man2html using the manual pages.
Time: 00:22:12 GMT, November 20, 2008

2. uname.2.man

Manpage of UNAME

UNAME

Section: Linux Programmer's Manual (2)
Updated: 2007-07-05
Index Return to Main Contents

NAME

uname - get name and information about current kernel

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[];
    char nodename[];
    char release[];
    char version[];
    char machine[];
#ifdef _GNU_SOURCE
    char domainname[];
#endif
};

The length of the arrays in a struct utsname is unspecified; 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 appropriately.

ERRORS

EFAULT: buf is not valid.

CONFORMING TO

SVr4, POSIX.1-2001. There is no uname() call in 4.3BSD.

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

NOTES

This is a system call, and the operating system presumably knows its name, release and version. It also knows what hardware it runs on. So, four of the fields of the struct are meaningful. On the other hand, the field nodename is meaningless: it gives the name of the present machine in some undefined network, but typically machines are in more than one network and have several names. Moreover, the kernel has no way of knowing about such things, so it has to be told what to answer here. The same holds for the additional domainname field.

To this end Linux uses the system calls sethostname(2) and setdomainname(2). Note that there is no standard that says that the hostname set by sethostname(2) is the same string as the nodename field of the struct returned by uname() (indeed, some systems allow a 256-byte hostname and an 8-byte nodename), but this is true on Linux. The same holds for setdomainname(2) and the domainname field.

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(...). Often 257 is chosen in order to have room for an internet hostname.

Part of the utsname information is also accessible via sysctl(2) and via /proc/sys/kernel/{ostype, hostname, osrelease, version, domainname}.

Underlying kernel interface

Over time, increases in the size of the utsuname 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.

COLOPHON

This page is part of release 2.78 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.