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

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

NAME         top

       gethostname, sethostname - get/set hostname

SYNOPSIS         top

       #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         top

       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
       array 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
       array 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         top

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

ERRORS         top

       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.
              (Before version 2.1, glibc uses EINVAL for this case.)

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

CONFORMING TO         top

       SVr4, 4.4BSD  (these interfaces first appeared in 4.2BSD).
       POSIX.1-2001 specifies gethostname() but not sethostname().

NOTES         top

       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.

       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.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 3.75 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)