mirror of https://github.com/mkerrisk/man-pages
127 lines
3.7 KiB
Groff
127 lines
3.7 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified 1995-07-22 by Michael Chastain <mec@duracef.shout.net>:
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.\" 'gethostname' is real system call on Linux/Alpha.
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.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
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.\" Modified 2000-06-04, 2001-12-15 by aeb
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.\" Modified 2004-06-17 by mtk
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.\"
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.TH GETHOSTNAME 2 2004-06-17 "Linux 2.6.7" "Linux Programmer's Manual"
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.SH NAME
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gethostname, sethostname \- get/set host name
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.SH SYNOPSIS
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.B #include <unistd.h>
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.sp
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.BI "int gethostname(char *" name ", size_t " len );
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.br
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.BI "int sethostname(const char *" name ", size_t " len );
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.SH DESCRIPTION
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These system calls are used to access or to change the host name of the
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current processor.
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The
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.BR gethostname ()
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system call returns a null-terminated hostname (set earlier by
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.BR sethostname ())
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in the array \fIname\fP that has a length of \fIlen\fP bytes.
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In case the null-terminated hostname does not fit, no error is
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returned, but the hostname is truncated.
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It is unspecified
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whether the truncated hostname will be null-terminated.
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.SH "RETURN VALUE"
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On success, zero is returned.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EFAULT
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.I name
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is an invalid address.
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.TP
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.B EINVAL
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.I len
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is negative or, for
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.BR sethostname (),
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.I len
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is larger than the maximum allowed size,
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or, for
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.BR gethostname ()
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on Linux/i386,
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.I len
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is smaller than the actual size.
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(In this last case glibc 2.1 uses ENAMETOOLONG.)
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.TP
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.B EPERM
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For
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.BR sethostname (),
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the caller did not have the
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.B CAP_SYS_ADMIN
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capability.
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.SH "CONFORMING TO"
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SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD).
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POSIX.1-2001 specifies
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.BR gethostname ()
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but not
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.BR sethostname ().
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.SH NOTES
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SUSv2 guarantees that `Host names are limited to 255 bytes'.
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POSIX.1-2001 guarantees that `Host names (not including
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the terminating null byte) are limited to HOST_NAME_MAX bytes'.
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.SH "GLIBC NOTES"
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The GNU C library implements
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.BR gethostname ()
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as a library function that calls
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.BR uname (2)
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and copies up to
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.I len
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bytes from the returned
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.I nodename
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field into
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.IR name .
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Having performed the copy, the function then checks if the length of the
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.I nodename
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was greater than or equal to
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.IR len ,
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and if it is, then the function returns \-1 with
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.I errno
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set to
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.BR ENAMETOOLONG .
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Versions of glibc before 2.2
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.\" At least glibc 2.0 and 2.1, older versions not checked
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handle the case where the length of the
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.I nodename
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was greater than or equal to
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.IR len
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differently: nothing is copied into
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.I name
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and the function returns \-1 with
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.I errno
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set to
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.BR ENAMETOOLONG .
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.SH "SEE ALSO"
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.BR getdomainname (2),
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.BR setdomainname (2),
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.BR uname (2)
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