.\" Copyright, The contributors to the Linux man-pages project .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .TH getdomainname 2 2025-05-06 "Linux man-pages 6.14" .SH NAME getdomainname, setdomainname \- get/set NIS domain name .SH LIBRARY Standard C library .RI ( libc ,\~ \-lc ) .SH SYNOPSIS .nf .B #include .P .BI "int getdomainname(char *" name ", size_t " size ); .BI "int setdomainname(const char *" name ", size_t " size ); .fi .P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .P .BR getdomainname (), .BR setdomainname (): .nf Since glibc 2.21: .\" commit 266865c0e7b79d4196e2cc393693463f03c90bd8 _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) .fi .SH 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. .P .BR setdomainname () sets the domain name to the value given in the character array .IR name . The .I size argument specifies the number of bytes in .IR name . (Thus, .I name does not require a terminating null byte.) .P .BR getdomainname () returns the null-terminated domain name in the character array .IR name , which has a size of .I size bytes. If the null-terminated domain name requires more than .I len bytes, .BR getdomainname () returns the first .I len bytes (glibc) or gives an error (libc). .SH RETURN VALUE On success, zero is returned. On error, \-1 is returned, and .I errno is set to indicate the error. .SH ERRORS .BR setdomainname () can fail with the following errors: .TP .B EFAULT .I name pointed outside of user address space. .TP .B EINVAL .I size was negative or too large. .TP .B EPERM The caller did not have the .B CAP_SYS_ADMIN capability in the user namespace associated with its UTS namespace (see .BR namespaces (7)). .P .BR getdomainname () can fail with the following errors: .TP .B EINVAL For .BR getdomainname () under libc: .I name is NULL or .I name is equal or longer than .I size bytes. .SH VERSIONS On most Linux architectures (including x86), there is no .BR getdomainname () system call; instead, glibc implements .BR getdomainname () as a library function that returns a copy of the .I domainname field returned from a call to .BR uname (2). .SH STANDARDS None. .\" But they appear on most systems... .SH 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. .SH SEE ALSO .BR gethostname (2), .BR sethostname (2), .BR uname (2), .BR uts_namespaces (7)