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.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified 1995-07-22 by Michael Chastain <mec@duracef.shout.net>:
.\" 'gethostname' is real system call on Linux/Alpha.
.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 2000-06-04, 2001-12-15 by aeb
.\" Modified 2004-06-17 by mtk
.\"
.TH GETHOSTNAME 2 2007-07-26 "Linux" "Linux Programmer's Manual"
.SH NAME
gethostname, sethostname \- get/set hostname
.SH SYNOPSIS
.B #include <unistd.h>
.sp
.BI "int gethostname(char *" name ", size_t " len );
.br
.BI "int sethostname(const char *" name ", size_t " len );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR gethostname ():
_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
.br
.BR sethostname ():
_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
.ad b
.SH DESCRIPTION
These system calls are used to access or to change the hostname of the
current processor.
The
.BR gethostname ()
system call returns a null-terminated hostname (set earlier by
.BR sethostname ())
in the array \fIname\fP that has a length of \fIlen\fP 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.
.SH "RETURN VALUE"
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EFAULT
.I name
is an invalid address.
.TP
.B EINVAL
.I len
is negative or, for
.BR sethostname (),
.I len
is larger than the maximum allowed size,
or, for
.BR gethostname ()
on Linux/i386,
.I len
is smaller than the actual size.
(In this last case glibc 2.1 uses
.BR ENAMETOOLONG .)
.TP
.B EPERM
For
.BR sethostname (),
the caller did not have the
.B CAP_SYS_ADMIN
capability.
.SH "CONFORMING TO"
SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD).
POSIX.1-2001 specifies
.BR gethostname ()
but not
.BR sethostname ().
.SH 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
.B HOST_NAME_MAX
bytes".
.SS Glibc Notes
The GNU C library implements
.BR gethostname ()
as a library function that calls
.BR uname (2)
and copies up to
.I len
bytes from the returned
.I nodename
field into
.IR name .
Having performed the copy, the function then checks if the length of the
.I nodename
was greater than or equal to
.IR len ,
and if it is, then the function returns \-1 with
.I errno
set to
.BR ENAMETOOLONG .
Versions of glibc before 2.2
.\" At least glibc 2.0 and 2.1, older versions not checked
handle the case where the length of the
.I nodename
was greater than or equal to
.I len
differently: nothing is copied into
.I name
and the function returns \-1 with
.I errno
set to
.BR ENAMETOOLONG .
.SH "SEE ALSO"
.BR getdomainname (2),
.BR setdomainname (2),
.BR uname (2)
.SH COLOPHON
This page is part of release 3.05 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
|
