print debug message in linux system

print_msg.c

static void printf_msg(const char *fmt, ...)
{
    if (fmt == NULL)
        return;

    va_list ap;
#define CMD_SIZE    512
    char tmp_buf[CMD_SIZE];
    char cmd[CMD_SIZE+128];

    memset(tmp_buf, 0x0, sizeof(tmp_buf));
    va_start(ap, fmt);
    vsnprintf(tmp_buf, CMD_SIZE, fmt, ap);
    va_end(ap);

    sprintf(cmd, "/usr/bin/logger -i -t app_name '%s'", tmp_buf);

    system(cmd);
}