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GETHOSTNAME(2)		   Linux Programmer's Manual		GETHOSTNAME(2)

NAME
       gethostname, sethostname	- get/set hostname

SYNOPSIS
       #include	<unistd.h>

       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)):

       gethostname():
	   Since glibc 2.12: _BSD_SOURCE || _XOPEN_SOURCE >= 500
	   || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200112L
       sethostname():
	   _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

DESCRIPTION
       These  system calls are used to access or to change the hostname	of the
       current processor.

       sethostname() sets the hostname to the value given in the character ar-
       ray  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 ar-
       ray  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.

RETURN VALUE
       On  success,  zero is returned.	On error, -1 is	returned, and errno is
       set appropriately.

ERRORS
       EFAULT name is an invalid address.

       EINVAL len is negative or, for sethostname(), len is  larger  than  the
	      maximum allowed size.

       ENAMETOOLONG
	      (glibc gethostname()) len	is smaller than	the actual size.  (Be-
	      fore version 2.1,	glibc uses EINVAL for this case.)

       EPERM  For sethostname(), the caller did	not have the CAP_SYS_ADMIN ca-
	      pability.

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;  in-
       stead, it implements gethostname() as a library function	that calls un-
       ame(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.

       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-
       TOOLONG.

SEE ALSO
       getdomainname(2), setdomainname(2), uname(2)

COLOPHON
       This  page  is  part of release 3.74 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       http://www.kernel.org/doc/man-pages/.

Linux				  2014-08-19			GETHOSTNAME(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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