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       gethostname, sethostname - get/set host name


       #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(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
       sethostname(): _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)


       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.


       EFAULT name is an invalid address.

       EINVAL 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.)

       EPERM  For  sethostname(),  the  caller  did not have the CAP_SYS_ADMIN


       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".

   Glibc Notes
       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


       getdomainname(2), setdomainname(2), uname(2)


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