datasend.c

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdio.h>

#define DATA "This is from An Introductory 4.3BSD Interprocess Communication Tutorial"

/*
 * Here I send a datagram to a receiver whose name I get from
 * the command line arguments. The form of the command line
 * is udgramsend pathname.
 */

main(argc, argv)
    int argc;
    char *argv[];
{
    int sock;
    struct sockaddr_un name;

    /* Create socket on which to send. */
    sock = socket(AF_UNIX, SOCK_DGRAM, 0);
    if (sock < 0) {
        perror("opening datagram socket");
        exit(1);
    }
    /* Construct name of socket to send to. */
    name.sun_family = AF_UNIX;
    strcpy(name.sun_path, argv[1]);
    /* Send message. */
    if (sendto(sock, DATA, sizeof(DATA), 0,
        &name, sizeof(struct sockaddr_un)) < 0) {
            perror("sending datagram message");
    }
    close(sock);
}