Originální popis anglicky:
uname - get name and information about current kernel
Návod, kniha: Linux Programmer's Manual
#include <sys/utsname.h>
int uname(struct utsname *buf);
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 NUL-terminated.
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- EFAULT
- buf is not valid.
SVr4, SVID, POSIX, X/OPEN. There is no
uname call in BSD 4.3.
The
domainname member (the NIS or YP domain name) is a GNU extension.
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.
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.
Part of the utsname information is also accessible via
sysctl and via
/proc/sys/kernel/{
ostype,
hostname,
osrelease,
version,
domainname}.
uname(1),
getdomainname(2),
gethostname(2)
