【autorun.sh】
cd /home/octopus/Programs/powerlog
./powerlog2 on

【conn.h】
#define SERVER_NAME "localhost"
#define DB_USER "server"
#define DB_PASSWORD "PASSWORD"
#define DB_NAME "server"

【IP.txt】
192.168.0.4

【logview.c】
#include <mysql/mysql.h>
#include <stdio.h>
#include "conn.h"

void putstr(char *s, FILE *fp, char display)
{
    fputs(s, fp);
    fputc('\n', fp);
    if (display == 1)
        puts(s);
}

int main(int argc, char *argv[])
{
    char ch;
    char IP[16];
    char line[100];
    char sql[150];
    int i = 0;
    FILE *fp;
    MYSQL conn;
    MYSQL_RES *rs;
    MYSQL_ROW row;
   
    /* Get IP Address */
    if ((fp = fopen("IP.txt", "r")) == NULL)
    {
        printf("Cannot open the file for IP Address.\n");
        return 1;
    }
    while (ch = fgetc(fp), !feof(fp))
    {
        if ((ch >= '0' && ch <= '9') || ch == '.')
            IP[i++] = ch;
        else
            break;
        if (i == sizeof(IP) - 1)
            break;
    }
    IP[i] = '\0';
    fclose(fp);
   
    /* Open Log File */
    if ((fp = fopen("powerlog.txt", "w")) == NULL)
    {
        printf("Cannot open the file.\n");
        return 2;
    }
    printf("Powerlog Version 2.3\n");
    putstr("ID\tTIME", fp, 1);
   
    /* Init MySQL Connection */
    mysql_init(&conn);
    if (!mysql_real_connect(&conn, SERVER_NAME, DB_USER, DB_PASSWORD, DB_NAME, 0, NULL, 0))
    {
        printf("Cannot connect to the database server.\n");
        return 3;
    }
    mysql_set_character_set(&conn, "utf8");
   
    /* Query */
    sprintf(sql, "SELECT LogID, LogTime FROM PowerLog WHERE LogFlag = 'POWER ON' AND ComputerIP = '%s' ORDER BY LogTime DESC", IP);
    mysql_query(&conn, sql);
    rs = mysql_store_result(&conn);
    for (i = 0; row = mysql_fetch_row(rs); i++)
    {
        sprintf(line, "%d\t%s", atoi(row[0]), row[1]);
        putstr(line, fp, (i < 20));
    }
    mysql_free_result(rs);
    fclose(fp);
   
    mysql_close(&conn);
    return 0;
}

【Makefile】
MYSQL = -lmysqlclient

powerlog2: conn.h temperature.h temperature.c UART.h UART.c powerlog2.c
    gcc temperature.c UART.c powerlog2.c -o powerlog2 $(MYSQL)

logview: conn.h logview.c
    gcc logview.c -o logview $(MYSQL)

【powerlog2.c】
#include <mysql/mysql.h>
#include <stdio.h>
#include <string.h>
#include "conn.h"
#include "UART.h"

int main(int argc, char *argv[])
{
    char sql[200];
    char *sql_err;
    char temp_str[10];
    char temp_str_buffer[120] = {0};
    char uart_open = 1;
    float temp;
    int i = 10;
    MYSQL conn;
    MYSQL_RES *rs;
    MYSQL_ROW row;
   
    if (UART_Open() == 0)
        uart_open = 0;
    mysql_init(&conn);
    if (!mysql_real_connect(&conn, SERVER_NAME, DB_USER, DB_PASSWORD, DB_NAME, 0, NULL, 0))
    {
        printf("Cannot connect to the database server.\n");
        return 3;
    }
    mysql_set_character_set(&conn, "utf8");
   
    printf("Powerlog Version 2.3\n");
    printf("Welcome\n");
   
    if (uart_open)
    {
        get_temperature(&temp); // avoid the first possible error value
        while (i--)
        {
            usleep(10000);
            get_temperature(&temp);
            get_temperature_str(&temp, temp_str);
            strcat(temp_str_buffer, temp_str);
        }
    }
    else
        strcpy(temp_str_buffer, "UART Unavailable");
       
    if (argc >= 2 && strcmp(argv[1], "on") == 0)
    {
        sprintf(sql, "INSERT INTO PowerLog (LogTime, LogFlag, Temperature) VALUES (NOW(), 'POWER ON', TRIM('%s'))", temp_str_buffer);
        sql_err = "INSERT INTO PowerLog (LogTime, LogFlag, Temperature) VALUES (NOW(), 'POWER ON', 'Query Error')";
    }
    else
    {
        // Just for debug
        sprintf(sql, "INSERT INTO PowerLog (LogTime, Temperature) VALUES (NOW(), '%s')", temp_str_buffer);
        sql_err = "INSERT INTO PowerLog (LogTime, Temperature) VALUES (NOW(), 'Query Error')";
    }
   
    i = mysql_query(&conn, sql);
    if (i == 1)
        mysql_query(&conn, sql_err);
   
    mysql_query(&conn, "SELECT NOW()");
    rs = mysql_store_result(&conn);
    row = mysql_fetch_row(rs);
    printf("MySQL Time: %s\n", row[0]);
    mysql_free_result(rs);
    mysql_close(&conn);
    if (uart_open)
        UART_Close();
    return 0;
}

【temperature.c】
#include <stdio.h>
#include <unistd.h>
#include "UART.h"
#include "temperature.h"

#define _BV(n) (1 << n)
#define TEMP_NEGATIVE _BV(4)
#define TEMP_ERROR _BV(6)

char buffer[513];

void get_temperature(float *temp)
{
    UART_Send(0x83);
    usleep(100000);
    UART_Receive(buffer);
    if (buffer[1] & TEMP_ERROR)
    {
        *temp = -999.99;
        return;
    }
    *temp = buffer[2] * 1.00 + buffer[3] * 0.01;
    if (buffer[1] & TEMP_NEGATIVE)
        *temp = -*temp;
}

void get_temperature_str(float *temp, char *s)
{
    sprintf(s, "%.2f℃\t", *temp);
}

【temperature.h】
void get_temperature(float *temp);
void get_temperature_str(float *temp, char *s);

【UART.c】
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> // UNIX Standard Function Definitions
#include <fcntl.h> // File Control Definitions
#include <errno.h> // File Control Definitions
#include <termios.h> // POSIX Terminal Control Definitions
#include "UART.h"

struct termios tty;
struct termios tty_old;
int UART_id = 0;

int UART_Open(void)
{
    memset(&tty, 0, sizeof(tty));
    UART_id = open(UART_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
    if (UART_id < 0)
    {
        printf("Warning: Cannot open the serial port!\n");
        return 0;
    }
  
    /* Error Handling */
    if (tcgetattr(UART_id, &tty) != 0)
    {
        printf("Error: %d from tcgetattr: %s \n", errno,strerror(errno));
        return 0;
    }
  
    /* Save old tty parameters */
    tty_old = tty;
  
    /* Set Baud Rate */
    cfsetospeed(&tty, (speed_t)B9600);
    cfsetispeed(&tty, (speed_t)B9600);
  
    /* Setting other Port Stuff */
    tty.c_cflag &= ~PARENB; // Make 8n1
    tty.c_cflag &= ~CSTOPB;
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;
  
    tty.c_cflag &= ~CRTSCTS; // no flow control
    tty.c_cc[VMIN] = 1; // read doesn't block
    tty.c_cc[VTIME] = 5; // 0.5 second read timeout
    tty.c_cflag |= CREAD | CLOCAL; // turn on READ & ignore ctrl lines
  
    /* Make raw */
    cfmakeraw(&tty);
  
    /* Flush Port, then applies attributes */
    tcflush(UART_id, TCIFLUSH);
    if (tcsetattr(UART_id, TCSANOW, &tty) != 0)
    {
        printf("Error: %d from tcgetattr\n", errno);
        return 0;
    }
  
    return UART_id;
}

void UART_Send(unsigned char Byte)
{
    write(UART_id, &Byte, 1);
    // It was definitely not necessary to write byte per byte, also int n_written = write( UART_id, cmd, sizeof(cmd) -1) worked fine.
}

int UART_Receive(char* buf)
{
    int len = read(UART_id, buf, 512);
    buf[len] = '\0';
    return len;
}

void UART_Close()
{
    close(UART_id);
}

【UART.h】
#define UART_PORT "/dev/ttyUSB0"

int UART_Open(void);
void UART_Send(unsigned char Byte);
int UART_Receive(char* buf);
void UART_Close();

注意：编译时，powerlog2和logview这两个程序都要编译，并且要将autorun.sh设为开机启动。最后还要设置串口设备的访问权限，方法请参阅：
http://blog.csdn.net/cokewei/article/details/8281239

【MySQL数据表的结构】
CREATE TABLE `PowerLog` (
 `LogID` int(11) NOT NULL AUTO_INCREMENT,
 `LogTime` datetime NOT NULL,
 `LogFlag` varchar(20) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'TEST',
 `LogTimeZone` varchar(10) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'UTC+8',
 `ComputerIP` varchar(20) COLLATE utf8_unicode_ci NOT NULL DEFAULT '192.168.0.4',
 `Temperature` varchar(100) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'NO DATA',
 PRIMARY KEY (`LogID`)
) ENGINE=InnoDB AUTO_INCREMENT=1159 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

其实，那个TRIM('%s')中的TRIM是可以去掉的