NAME

       getdomainname, setdomainname - get/set NIS domain name

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       int getdomainname(size_t size;
                         char name[size], size_t size);
       int setdomainname(size_t size;
                         const char name[size], size_t size);

   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.  More precisely,
       they operate on the NIS domain name associated with the calling process's UTS namespace.

       setdomainname() sets the domain name to the value given in the character array name.  The  size  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 size of
       size 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 to indicate the error.

ERRORS

       setdomainname() can fail with the following errors:

       EFAULT name pointed outside of user address space.

       EINVAL size 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 equal or longer than size bytes.

VERSIONS

       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).

STANDARDS

       None.

HISTORY

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

SEE ALSO

       gethostname(2), sethostname(2), uname(2), uts_namespaces(7)

Linux man-pages 6.15                               2025-06-28                                   getdomainname(2)