gethostname, sethostname — get/set host name
#include <unistd.h>
int
gethostname( |
char * | name, |
size_t | len) ; |
int
sethostname( |
const char * | name, |
size_t | len) ; |
These system calls are used to access or to change the
host name of the current processor. The gethostname
() system call returns a
null-terminated hostname (set earlier by sethostname
()) in the array name
that has a length of
len
bytes. In case
the null-terminated hostname does not fit, no error is
returned, but the hostname is truncated. It is unspecified
whether the truncated hostname will be null-terminated.
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, or, for gethostname
() on Linux/i386,
len
is smaller
than the actual size. (In this last case glibc 2.1 uses
ENAMETOOLONG.)
For sethostname
(), the
caller did not have the CAP_SYS_ADMIN
capability.
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 null byte) are limited to HOST_NAME_MAX bytes'.
The GNU C library 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. 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.
getdomainname(2), setdomainname(2), uname(2)
|