int gethostname(char *name, size_t len);
int sethostname(const char *name, size_t len);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.12: _BSD_SOURCE || _XOPEN_SOURCE >= 500
|| /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200112L
_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
These system calls are used to access or to change the hostname of the
sethostname() sets the hostname 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.)
gethostname() returns the null-terminated hostname in the character
array name, which has a length of len bytes. If the null-terminated
hostname is too large to fit, then the name is truncated, and no error
is returned (but see NOTES below). POSIX.1-2001 says that if such
truncation occurs, then it is unspecified whether the returned buffer
includes a terminating null byte.
On success, zero is returned. On error, -1 is returned, and errno is
EFAULT name is an invalid address.
EINVAL len is negative or, for sethostname(), len is larger than the
maximum allowed size.
(glibc gethostname()) len is smaller than the actual size.
(Before version 2.1, glibc uses EINVAL for this case.)
EPERM For sethostname(), the caller did not have the CAP_SYS_ADMIN
SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD).
POSIX.1-2001 specifies gethostname() but not sethostname().
SUSv2 guarantees that "Host names are limited to 255 bytes".
POSIX.1-2001 guarantees that "Host names (not including the terminating
Versions of glibc before 2.2 handle the case where the length of the
nodename was greater than or equal to len differently: nothing is
copied into name and the function returns -1 with errno set to ENAME-
getdomainname(2), setdomainname(2), uname(2)
This page is part of release 3.35 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://man7.org/linux/man-pages/.
Linux 2010-09-26 GETHOSTNAME(2)
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