|GETHOSTNAME(2)||Linux Programmer's Manual||GETHOSTNAME(2)|
int gethostname(char *name, size_t len); int sethostname(const char *name, size_t len);
_XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L || /* Glibc 2.19 and earlier */ _BSD_SOURCE
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)
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 says that if such truncation occurs, then it is unspecified whether the returned buffer includes a terminating null byte.
- name is an invalid address.
- 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.)
- For sethostname(), the caller did not have the CAP_SYS_ADMIN capability in the user namespace associated with its UTS namespace (see namespaces(7)).
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 ENAMETOOLONG.