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  • 现象: 不管是输入命令 init 3 或者 init5 ,重启后都是直接进入图形界面...# inittab is no longer used when using systemd. # # ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM. # # Ctrl-Alt-D...

    现象:

    • 不管是输入命令 init 3 或者 init5 ,重启后都是直接进入图形界面
    • vim /etc/inittab 查看,内容如下:
    # inittab is no longer used when using systemd.
    #
    # ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
    #
    # Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
    #
    # systemd uses 'targets' instead of runlevels. By default, there are two main targets:
    #
    # multi-user.target: analogous to runlevel 3
    # graphical.target: analogous to runlevel 5
    #
    # To view current default target, run:
    # systemctl get-default
    #
    # To set a default target, run:
    # systemctl set-default TARGET.target
    

    解决方案:

    • 英文注释写的很清楚,大致就是用systemctl set-default   和 systemctl get-default 取代数字级别
    • # 查看当前运行级别
      systemctl get-default
      
      # 设置当前运行级别为3 (开机为命令行模式)
      systemctl set-default multi-user.target
      
      # 设置当前运行级别为5 (开机为图形界面)
      systemctl set-default graphical.target

       

    展开全文
  • 参考:https://unix.stackexchange.com/questions/507131/openssl-1-1-1b-warning-using-iter-or-pbkdf2-would-be-better-while-decrypting 加上-pbkdf2即可。 openssl aes-256-cbc -salt -pbkdf2 -in name -out ...

    参考:https://unix.stackexchange.com/questions/507131/openssl-1-1-1b-warning-using-iter-or-pbkdf2-would-be-better-while-decrypting

    加上-pbkdf2即可。

    openssl aes-256-cbc -salt -pbkdf2 -in name -out name.aes
    
    openssl aes-256-cbc -d -salt -pbkdf2 -in name.aes -out name
    

    但是要注意没有用-pbkdf2加密的文件不能用-pbkdf2选项解密。

    展开全文
  • C++ 11 using和typedef区别

    2019-09-05 11:04:46
    版权声明:本文为博主原创文章,遵循 CC 4.0 BY-SA 版权协议,转载请附上原文出处链接本声明。 ...
    版权声明:本文为博主原创文章,遵循 CC 4.0 BY-SA 版权协议,转载请附上原文出处链接和本声明。
    本文链接: https://blog.csdn.net/fpcc/article/details/54582670

    在普通的类型名定义时,理论上讲二者是没有区别的,标准上是这样说的:

    A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and the optional attribute-specifier-seq following the identifierappertains to that typedef-name. It has the same semantics as if it wereintroduced by the typedef specifier. In particular, it does not define a newtype and it shall not appear in the type-id

    类似于#define和typedef,举例如下:

    using WorkerProc= std::function<void(T*)>;

    typedef std::function<void(T*)>  WorkerProc;

    上面也提到了,二者是等价的。

    但也是有一些细微的区别的,从网上找了个例子

    // type alias can introduce a member typedef name

    template<typename T>

    struct Container {

       using value_type = T;

    };

    // which can be used in generic programming

    template<typename Container>

    void fn2(const Container& c)

    {

        typenameContainer::value_type n;

    }

    // 2016/08/25 补

    int main()

    {

       Container<int> c;

       fn2(c); // Container::value_type will be int in this function

       return 0;

    }

    红色的部分显示的表明这是一个类型名,而不是一个静态成员变量,否则会误认为其是一个静态成员变量。这个在Effective C++和C++模板里也有说明。

    细节很重要,但还是那句话,不要沉迷于细节。

    展开全文
  • using和typedef区别

    千次阅读 2017-01-17 14:19:22
    在普通的类型名定义时,理论上讲二者是没有区别的,标准上是这样说的: A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and ...

    在普通的类型名定义时,理论上讲二者是没有区别的,标准上是这样说的:

    A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and the optional attribute-specifier-seq following the identifierappertains to that typedef-name. It has the same semantics as if it wereintroduced by the typedef specifier. In particular, it does not define a newtype and it shall not appear in the type-id

    类似于#define和typedef,举例如下:

    using WorkerProc= std::function<void(T*)>;

    typedef std::function<void(T*)>  WorkerProc;

    上面也提到了,二者是等价的。

    但也是有一些细微的区别的,从网上找了个例子

    // type alias can introduce a member typedef name

    template<typename T>

    struct Container {

       using value_type = T;

    };

    // which can be used in generic programming

    template<typename Container>

    void fn2(const Container& c)

    {

        typename Container::value_type n;

    }

    // 2016/08/25 补

    int main()

    {

       Container<int> c;

       fn2(c); // Container::value_type will be int in this function

       return 0;

    }

    红色的部分显示的表明这是一个类型名,而不是一个静态成员变量,否则会误认为其是一个静态成员变量。这个在Effective C++和C++模板里也有说明。

    细节很重要,但还是那句话,不要沉迷于细节。

    展开全文
  • The resource http://localhost:8082/js/index.js was preloaded using link preload but not used within a few seconds from the window’s load event. Please make sure it has an appropriate as value and it ...
  • Comparison of optical and concentration feature used for fNIRS-based BCI system using HMM
  • 使用环境(蓝色粗体字为特别注意内容) 1、软件环境:Win7 32 bit,AD(Altium Designer) 10.39. 通常我们并不需要AD联网,在防火墙中将AD的联网权限禁用即可。 ...
  • (注意它之前代码的区别) #include int main() { using namespace std ; cout "Hello World!" ; return 0 ; } 这里的 using namespace std; 使得命名空间 std 下的所有命名在 main ...
  • 这是在一个新的项目里面启用java 8功能的,可能还存在其它方面的兼容问题。问题如下: 经过仔细检查build.gradle文件后发现是与 minifyEnabled 属性冲突了,改为false即可,如下图: Android ...
  • **AD软件出现“Your license is already used on computer “LAPTOP-F99R6OR1” using product “AltiumDesigner”. 您的许可证已经在使用产品“AltiumDesigner”的“膝上型计算机-F99R6OR1”上使用。 ”的解决办法 ...
  • OpenSSL library is not used

    万次阅读 2017-10-27 21:52:02
    问题: 在源码编译安装nginx的时候出现: Configuration summary  ... + OpenSSL library is not used   + using builtin md5 code   + sha1 library is not found   + using sys
  • 127.0.0.1:6380> info memory# Memoryused_memory:4189334840used_memory_rss:4692721664mem_fragmentation_ratio:1.12mem_allocator:jemalloc-3.6.0used_memory: Total number of bytes allocated by...
  • The book you hold in your hand is a natural evolution of my ...C#, or you’re just going deeper with Xamarin, this guide covers the most oft-used topics and techniques for Xamarin.Forms using XAML.
  • MySQL的查询执行计划中,Extra列经常会出现“Using where; Using index”。 MySQL官方手册解释: Using indexThe column information is retrieved from the table using only information in the index tree ...
  • The various packages and methods available in R will be used to explain the topics. In the end, readers will learn some of the latest technological advancements in building a scalable machine ...
  • Numerical Methods: Using MATLAB By 作者: George Lindfield – John Penny ISBN-10 书号: 0128122560 ISBN-13 书号: 9780128122563 Edition 版本: 4 出版日期: 2018-10-30 pages 页数: (608 ) $99.95 The fourth ...
  • Which two statements are true regarding the USING and ON clauses in table joins?... Both USING and ON clauses can be used for equijoins and nonequijoins. B. A maximum of one pair of co
  • RoboCon (as in Robot Control) is software used to control a robot using a laptop, or any other computer with a serial port. It includes the files necessary for developers to create a program of their ...
  • Game Programming using Qt 5 Beginner’s Guide, 2nd Edition.epub + code Author: P. Strakhov, W. Wysota, L. Haas 2018 Game Programming using Qt 5.x Beginner’s Guide – Second Edition: Design and build...
  • 使用类型别名有很多好处,它让复杂的类型名字变得简单明了、易于理解使用,还有助于程序员清楚地知道使用该类型的真实目的。在C++中,任何有效类型都可以有别名。 有两种方法可用于定义类型别名:传统的方法是...
  • Describe a number of computer network protocols and TCP/IP and OSI models, highlighting the networking devices used Explain a socket and its use in network programming, fostering the development of ...
  • As a domain expert, you will not only discover how machine learning is used in finance, healthcare, and retail, but also work through practical case studies where machine learning has been ...
  • Using index condition Using index

    千次阅读 2019-09-27 22:37:24
    Using index condition Tables are read by accessing index tuples and testing them first to determine whether to read full table rows. In this way, index information is used to defer (“push down”) ...
  • Bioinformatics Programming with Python can be used as a reference, for self-instruction, or as a companion book to help you through undergraduate courses in computer science, biology, and other life ...
  • Using PROC FREQ to List Values 1 Description of the Raw Data File PATIENTS.TXT 2 Using a DATA Step to Check for Invalid Values 7 Describing the VERIFY, TRIM, MISSING, and NOTDIGIT Functions 9 Using ...
  • Covering all levels of microwave circuit design from the elementary to the very advanced, the book systematically presents computer-aided methods for linear and nonlinear designs used in the design ...
  • Title: Problem Solving in Data Structures & Algorithms Using C++: Programming Interview Guide Language: English Publisher: CreateSpace Independent Publishing Platform Publication Date: 2017-01-08 ISBN...
  • 在已经保存的连接上上编辑,测试连接成功,但是点击连接就会一直提示connection is being used 这时候可以采取关闭连接编辑,然后保存就可以了,
  • The robot mentioning in this book is a service robot that can be used to serve food in home, hotels, and restaurant. From the beginning to end, the book discusses step-by-step procedures of building ...

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