Copyright © tutorialspoint.com
uname - get name and information about current kernel
#include <sys/utsname.h> |
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 ( ).
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
Tag | Description |
---|---|
EFAULT | buf is not valid. |
The domainname member (the NIS or YP domain name) is a GNU extension.
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}.
Copyright © tutorialspoint.com