|GETHOSTNAME(2)||Linux Programmer's Manual||GETHOSTNAME(2)|
NAME¶gethostname, sethostname - get/set hostname
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)
DESCRIPTION¶These system calls are used to access or to change the hostname of the current processor.
RETURN VALUE¶On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
- 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.
CONFORMING TO¶SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD). POSIX.1-2001 specifies gethostname() but not sethostname().
NOTES¶SUSv2 guarantees that "Host names are limited to 255 bytes". POSIX.1-2001 guarantees that "Host names (not including the terminating null byte) are limited to HOST_NAME_MAX bytes". On Linux, HOST_NAME_MAX is defined with the value 64, which has been the limit since Linux 1.0 (earlier kernels imposed a limit of 8 bytes).
C library/kernel ABI differences¶The GNU C library does not employ the gethostname() system call; instead, it implements gethostname() as a library function that calls uname(2) and copies up to len bytes from the returned nodename field into name. Having performed the copy, the function then checks if the length of the nodename was greater than or equal to len, and if it is, then the function returns -1 with errno set to ENAMETOOLONG; in this case, a terminating null byte is not included in the returned name.
SEE ALSO¶getdomainname(2), setdomainname(2), uname(2)
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