gethostname
Prototype:
#include <unistd.h>
int gethostname(char *name, size_t len);
General Description: Gets the local-host's name. The call places the result in the name parameter up to len-bytes.
Return Value: Zero (0) if everything goes well. If an error occurs, you can find the cause in errno.
Parameters
name The buffer to accept the name of the local host.
len The number of bytes available in name.
Possible Errors
EINVAL len is negative, or, for gethostname() on Linux/i386, len is smaller than the actual size.
EFAULT name is an invalid address.
Examples
char name[50];
if ( gethostname(name, sizeof(name)) != 0 )
    perror("gethostname() failed");
printf("My host is: %s\n", name);