linux使用C语言，通过MQTT发送以下JSON字符："ts": "2023-3-27 19:50:0", "d": [ { "tag": "MSTM", "value": "2023-3-27 19:50:0" }, { "tag": "VT", " value": 12.34 }, { "tag": "SPPRWL11", "value": 102.29 },

好的，您可以使用 Eclipse Paho MQTT C 客户端库来实现在 Linux 下通过 C 语言发送 MQTT 消息。以下是一个简单的示例代码，用于创建 JSON 字符串并将其发布到 MQTT 主题中：

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "MQTTClient.h"
#include "cJSON.h"

#define ADDRESS     "tcp://localhost:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "test"
#define QOS         1
#define TIMEOUT     10000L

int main(int argc, char* argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    char* payload = NULL;
    int rc;

    cJSON *root = cJSON_CreateObject();
    cJSON *data = cJSON_CreateArray();
    cJSON *item1 = cJSON_CreateObject();
    cJSON *item2 = cJSON_CreateObject();
    cJSON *item3 = cJSON_CreateObject();

    cJSON_AddStringToObject(root, "ts", "2023-3-27 19:50:0");

    cJSON_AddItemToArray(data, item1);
    cJSON_AddItemToArray(data, item2);
    cJSON_AddItemToArray(data, item3);

    cJSON_AddStringToObject(item1, "tag", "MSTM");
    cJSON_AddStringToObject(item1, "value", "2023-3-27 19:50:0");

    cJSON_AddStringToObject(item2, "tag", "VT");
    cJSON_AddNumberToObject(item2, "value", 12.34);

    cJSON_AddStringToObject(item3, "tag", "SPPRWL11");
    cJSON_AddNumberToObject(item3, "value", 102.29);

    payload = cJSON_PrintUnformatted(root);

    MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;

    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d\n", rc);
        exit(-1);
    }

    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    pubmsg.payload = payload;
    pubmsg.payloadlen = strlen(payload);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;

    MQTTClient_deliveryToken token;
    MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);
    printf("Waiting for publication of %s\n"
           "on topic %s for client with ClientID: %s\n",
           payload, TOPIC, CLIENTID);

    rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
    printf("Message with delivery token %d delivered\n", token);

    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);
    cJSON_Delete(root);
    free(payload);

    return rc;
}

这个程序使用 cJSON 库来创建 JSON 字符串，并使用 Eclipse Paho MQTT C 客户端库来连接到 MQTT 代理服务器并将消息发布到主题中。您需要在代码中更改 `ADDRESS`、`CLIENTID` 和 `TOPIC` 来适应您的实际情况。当您运行程序时，它将在终端输出消息发布的结果。