sock_un_client.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stddef.h>
#include <sys/socket.h>
#include <sys/un.h>
#include "error.h"

#define SOCK_PATH "/tmp/hello.socket"
#define BUFFER_SIZE 1024

int main(void)
{
    int fd, size;
    struct sockaddr_un peer_addr;
    socklen_t peer_addr_len;
    char buf[BUFFER_SIZE];

    memset(&peer_addr, 0, sizeof(peer_addr));
    peer_addr.sun_family = AF_UNIX;
    strcpy(peer_addr.sun_path, SOCK_PATH);

    // create socket
    if ((fd = socket(AF_UNIX,  SOCK_STREAM, 0)) < 0)
        err_sys("socket");

    // connect socket
    peer_addr_len = offsetof(struct sockaddr_un, sun_path) + strlen(peer_addr.sun_path);
    if(connect(fd, (struct sockaddr*)&peer_addr, peer_addr_len) < 0)
        err_sys("connect");

    // write
    strcpy(buf, "hello");
    write(fd, buf, strlen(buf));

    close(fd);
    unlink(SOCK_PATH);

    return EXIT_SUCCESS;
}