NAME

gethostname, sethostname — get/set name of current host

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>

int
gethostname(char *name, size_t namelen);

int
sethostname(const char *name, int namelen);

DESCRIPTION

The gethostname() function returns the standard host name for the current processor, as previously set by sethostname(). The namelen argument specifies the size of the name array. The returned name is null-terminated, unless insufficient space is provided.

The sethostname() function sets the name of the host machine to be name, which has length namelen. This call is restricted to the super-user and is normally used only when the system is bootstrapped.

Host names are limited in length to {sysconf(_SC_HOST_NAME_MAX)} characters, not including the trailing null, currently 255.

RETURN VALUES

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

The following errors may be returned by these calls:

[EFAULT]

The name or namelen argument gave an invalid address.

[ENAMETOOLONG]

The current host name is longer than namelen. (For gethostname() only.)

[EPERM]

The caller tried to set the host name and was not the super-user.

SEE ALSO

sysconf(3), sysctl(3)

STANDARDS

The gethostname() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”). Callers should be aware that {sysconf(_SC_HOST_NAME_MAX)} may be variable or infinite, but is guaranteed to be no less than {_POSIX_HOST_NAME_MAX}. On older systems, this limit was defined in the non-standard header <sys/param.h> as MAXHOSTNAMELEN, and counted the terminating null. The sethostname() function and the error returns for gethostname() are not standardized.

HISTORY

The gethostname() function appeared in 4.2BSD. The namelen argument to gethostname() was changed to size_t in FreeBSD 5.2 for alignment with IEEE Std 1003.1-2001 (“POSIX.1”).