|GETHOSTID(3)||Linux Programmer's Manual||GETHOSTID(3)|
int sethostid(long hostid);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.21: _DEFAULT_SOURCE In glibc 2.19 and 2.20: _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500) Up to and including glibc 2.19: _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
The sethostid() call is restricted to the superuser.
On success, sethostid() returns 0; on error, -1 is returned, and errno is set to indicate the error.
- The caller did not have permission to write to the file used to store the host ID.
- The calling process's effective user or group ID is not the same as its corresponding real ID.
|gethostid ()||Thread safety||MT-Safe hostid env locale|
|sethostid ()||Thread safety||MT-Unsafe const:hostid|
POSIX.1-2001 and POSIX.1-2008 specify gethostid() but not sethostid().
In the glibc implementation, if gethostid() cannot open the file containing the host ID, then it obtains the hostname using gethostname(2), passes that hostname to gethostbyname_r(3) in order to obtain the host's IPv4 address, and returns a value obtained by bit-twiddling the IPv4 address. (This value may not be unique.)