View Source: gethostname(2) - Waikato Linux Users Group

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!!NAME

gethostname - get host name
!!SYNOPSIS
 __#include <unistd.h>__
 __int gethostname(char *__''name''__, size_t__ ''len''__);__

!!DESCRIPTION
These functions are used to access or to change the host name of the current processor.  Note, that on the Internet each interface has a at least one address, and names are associated with addresses, so a machine may (and usually does) have multiple names.  gethostname(2) will return the one that the machine identifies itself as.

!!RETURN VALUE
On success, zero is returned. On error, -1 is returned, and ''errno'' is set appropriately.

!!ERRORS
;[EINVAL]: ''len'' is negative or, on Linux/i386, ''len'' is smaller than the actual size. (In this last case glibc 2.1 uses [ENAMETOOLONG].)
;[EFAULT]: ''name'' is an invalid address.
;[ENAMETOOLONG]: ''len'' is smaller than the length of the hostname

!!CONFORMING TO
SVr4, 4.4BSD (this function first appeared in 4.2BSD). POSIX.1 does not define these functions, but ISO/IEC 9945-1:1990 mentions them in B.4.4.1.

!!BUGS
According to the SUSv2, gethostname(2) must return ''len'' bytes (a truncated hostname, NUL-terminated or not) when the hostname is longer. Linux/Alpha (which has a system call gethostname(2)) complies with this requirement, but libc and glibc on Linux/i386 only return an error in this case.

!!NOTES
The definition of success varies. SUSv2 defines ''gethostname()'' as `return possibly truncated hostname', and having a small ''len'' does not cause an error return. Of course it must be possible to be certain that one has obtained the full hostname, and to this end
SUSv2 guarantees that `Host names are limited to 255 bytes'.

!!EXAMPLE
 #include <unistd.h>
 #include <malloc.h>
 #include <stdio.h>
 #include <string.h>

 int main(int argc,char **argv)
 {
         char domain[[256];
         int ret=gethostname(domain,sizeof(domain));
         if (ret==-1) {
                 perror("gethostname");
                 return 1;
         }
         printf("%s\n",domain);
         return 0;
 }


!!SEE ALSO
getdomainname(2), setdomainname(2), uname(2)

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Last edited on Friday, March 18, 2005 9:50:03 pm by "MichalMatyska"

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