mysql backup

#include "stdio.h"
#include "stdlib.h"
#include "time.h"
#include "string.h"
#include <fcntl.h>
#include <sys/types.h>

void backup(void)
{
    char name[20];
    char cmd[256];
    time_t   now;
    struct tm  *b;

    memset(name,0,20);
    memset(cmd,0,256);

    time(&now);
    b = gmtime(&now);

    strcat(name,"backup-");
    sprintf(name + strlen(name),"%d",1900+b->tm_year);
    sprintf(name + strlen(name),"%d",b->tm_mon+1);
    sprintf(name + strlen(name),"%d",b->tm_mday);
    //printf("%s",name);
    //printf("\n");

    strcat(cmd,"mysqldump --user=hlkj --password=hlkj --lock-all-tables --all-databases > ");
    strcat(cmd,name);
    strcat(cmd,".sql\n");

    strcat(cmd,"tar zcvf ");
    strcat(cmd,name);
    strcat(cmd,".tar.gz ");
    strcat(cmd,name);
    strcat(cmd,".sql\n");

    strcat(cmd,"mv -f ");
    strcat(cmd,name);
    strcat(cmd,".tar.gz  /var/www/html/MySQL_Backup\n");

    strcat(cmd,"rm -f ");
    strcat(cmd,name);
    strcat(cmd,".sql");

    //printf("%d,%s",strlen(cmd),cmd);
    //printf("\n");

    system(cmd);

}
int checkOnly()
{
    const char filename[]  = "./_lock";
    int fd = open (filename, O_WRONLY | O_CREAT , 0644);
    int flock = lockf(fd, F_TLOCK, 0 );
    if (fd == -1) {
        return 0;
    }
    if (flock == -1) {
        return 0;
    }    
    return 1;
}

int main(int argc, char *argv[])
{
    int i=0;
    if(checkOnly())	printf("this running......  !\n");    
    else
    {
	printf("this is running,plese closed and restart !\nexit this!\r\n") ;
        exit(0);        
    }

    while(1)
    {
        i++;
        sleep(3600);

        if(i>24)
        {
            i=0;
            backup();
        }
    }
    return 0;
}