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sethostname(2) [linux man page]

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 || _POSIX_C_SOURCE >= 200112L Before glibc 2.12: _BSD_SOURCE || _XOPEN_SOURCE >= 500 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 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
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. (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
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). Glibc Notes 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
getdomainname(2), setdomainname(2), uname(2) COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2010-09-20 GETHOSTNAME(2)

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

NAME
getdomainname, setdomainname - get/set domain name SYNOPSIS
#include <unistd.h> int getdomainname(char *name, size_t len); int setdomainname(const char *name, size_t len); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getdomainname(), setdomainname(): _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500) DESCRIPTION
These functions are used to access or to change the domain name of the host system. setdomainname() sets the domain name 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.) getdomainname() returns the null-terminated domain name in the character array name, which has a length of len bytes. If the null-termi- nated domain name requires more than len bytes, getdomainname() returns the first len bytes (glibc) or gives an error (libc). RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS
setdomainname() can fail with the following errors: EFAULT name pointed outside of user address space. EINVAL len was negative or too large. EPERM the caller is unprivileged (Linux: does not have the CAP_SYS_ADMIN capability). getdomainname() can fail with the following errors: EINVAL For getdomainname() under libc: name is NULL or name is longer than len bytes. CONFORMING TO
POSIX does not specify these calls. NOTES
Since Linux 1.0, the limit on the length of a domain name, including the terminating null byte, is 64 bytes. In older kernels, it was 8 bytes. On most Linux architectures (including x86), there is no getdomainname() system call; instead, glibc implements getdomainname() as a library function that returns a copy of the domainname field returned from a call to uname(2). SEE ALSO
gethostname(2), sethostname(2), uname(2) COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2009-09-27 GETDOMAINNAME(2)
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