GETDOMAINNAME(2)

NAME
getdomainname, setdomainname - get/set NIS domain name

SYNOPSIS
#include <unistd.h>

int getdomainname(char *name, size_t len);
int setdomainname(const char *name, size_t len);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getdomainname(), setdomainname():
    Since glibc 2.21:
        _DEFAULT_SOURCE
    In glibc 2.19 and 2.20:
        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
    Up to and including glibc 2.19:
        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

DESCRIPTION
These functions are used to access or to change the NIS domain name of the host system.

setdomainname() sets the domain name to the value given in the character array name. The len argument specifies the number of bytes in name. (Thus, name does not require a terminating null byte.)

getdomainname() returns the null-terminated domain name in the character array name, which has a length of len bytes. If the null-terminated domain name requires more than len bytes, getdomainname() returns the first len bytes (glibc) or gives an error (libc).

RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS
setdomainname() can fail with the following errors:

EFAULT
    name pointed outside of user address space.

EINVAL
    len was negative or too large.

EPERM
    The caller did not have the CAP_SYS_ADMIN capability in the user namespace associated with its UTS namespace (see namespaces(7)).

getdomainname() can fail with the following errors:

EINVAL
    For getdomainname() under libc: name is NULL or name is longer than len bytes.

CONFORMING TO
POSIX does not specify these calls.

NOTES
Since Linux 1.0, the limit on the length of a domain name, including the terminating null byte, is 64 bytes. In older kernels, it was 8 bytes.

On most Linux architectures (including x86), there is no getdomainname() system call; instead, glibc implements getdomainname() as a library function that returns a copy of the domainname field returned from a call to uname(2).

SEE ALSO
gethostname(2), sethostname(2), uname(2)

COLOPHON
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