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Annotated edit history of uname(2) version 2, including all changes. View license author blame.
Rev Author # Line
1 perry 1 !!NAME
2
3 uname - get name and information about current kernel
2 CraigBox 4
1 perry 5 !!SYNOPSIS
6
2 CraigBox 7 __#include <sys/utsname.h>__ %%%
8 __int uname(struct utsname *__buf__);__
1 perry 9
10 !!DESCRIPTION
11
2 CraigBox 12 uname returns system information in the structure pointed to by buf. The utsname struct is defined in <sys/utsname.h>:
13 struct utsname {
14 char sysname[];
15 char nodename[];
16 char version[];
17 char machine[];
18 #ifdef _GNU_SOURCE
19 char domainname[];
20 #endif
21 };
1 perry 22
2 CraigBox 23 The length of the arrays in a struct utsname is unspecified; the fields are [NUL]-terminated.
1 perry 24
25 !!RETURN VALUE
26
2 CraigBox 27 On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
1 perry 28
29 !!ERRORS
30
2 CraigBox 31 ;[EFAULT]:buf is not valid.
1 perry 32
2 CraigBox 33 !!CONFORMING TO
1 perry 34
2 CraigBox 35 SVr4, SVID, POSIX, X/OPEN. There is no uname call in BSD 4.3.
1 perry 36
2 CraigBox 37 The domainname member (the NIS or YP domain name) is a GNU extension.
1 perry 38
2 CraigBox 39 !!NOTES
1 perry 40
2 CraigBox 41 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.
1 perry 42
2 CraigBox 43 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.
1 perry 44
2 CraigBox 45 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.
46
47 There have been three Linux system calls uname(). The first one used length 9, the second one used 65, the third one also uses 65 but adds the domainname field.
1 perry 48
2 CraigBox 49 Part of the utsname information is also accessible via sysctl and via /proc/sys/kernel/{ostype, hostname, osrelease, version, domainname}.
50
51 !!SEE ALSO
1 perry 52
2 CraigBox 53 uname(1), getdomainname(2), gethostname(2)
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