• What if Linux forgets the root password


    When you forget the root password or the root password is tampered with, there is no remote solution. You must enter the computer room and connect the keyboard and monitor to the server for field operation. Taking rhel6.6 as an example, the field operation steps are divided into seven steps, as follows Press and hold […]

  • How to manually release swap, buffer and cache in Linux


    Author: Darren_ WenLink: https://blog.51cto.com/wendas…This paper introduces the principle and operation of Linux memory mechanism, virtual memory swap, buffer / cache release and so on. 1、 What is the memory mechanism of Linux? We know that reading and writing data directly from physical memory is much faster than reading and writing data from hard disk. Therefore, […]

  • How to print word document through Java


    This article describes how to use Java programs to print word documents. Printing can be divided into two ways: one is to print to a physical printer; the other is to print to a virtual printer. Tools used: Spire.Doc for Java Test environment: Intellij Idea2019.1 JDK 1.8.0 Spire.Doc.jar Jar package acquisition and import: Mode 1:Download […]

  • LVM logic volume management (Illustrated)!


    1.1. Foreword Every Linux user will encounter such a dilemma when installing Linux: how to accurately evaluate and allocate the capacity of each hard disk partition when partitioning the system, because the system administrator should not only consider the capacity required by a certain partition at present, but also foresee the maximum capacity that the […]

  • Oracle operation and maintenance — 03. Commands for viewing table space information in Oracle Database


    1、 Table space usage size query 1.1 the data dictionary tables in the database system obtain the relevant information of the table space; select   a. A1 table space name,   c. C2 type,   c. Zone C3 management,   b. B2 / 1024 / 1024 table space size m,   (b.b2-a.a2) / 1024 / 1024 used m,   Utilization of […]

  • Linux Btrfs file system


    Btrfs has many names: B-tree FS; butter FS; better FS The open source protocol is GPL, which was developed by Oracle in 2007 Core features: Multi physical volume support, Btrfs can be composed of multiple physical volumes; support raid, can be online, add, remove, modify Copy on write: the contents of the file before modification […]

  • I hear you want to experience Ubuntu?


    I hear you want to experience Ubuntu? Background: asUbuntuDeep users of the system, all the way through, still encountered a lot of trouble (stepping on a lot of holes), whether it is the installation of the system, or the configuration of the desktop. So, here’s the planUbuntuThe whole process of installation and configuration is summarized […]

  • Fundamentals of computer operating system (10) — virtual memory for storage management


    introduction This is the tenth article,Virtual memory for storage managementBefore we get to know it, there is a problem. A game has more than ten gigabytes, and the physical memory is only 4G. So how does this game run? In order to solve this problem, we need to introduce in this articlevirtual memoryKnowledge of Virtual […]

  • Magical win10 networking problem under wmware


    Today, we encountered a magical win10 networking problem in VMware. All kinds of troubles were solved finally. Here is a record: The environment is as follows: Physical machine: win10 home x64 Virtual machine platform: wmware 15. X Virtual machine: win10 enterprise x64 Networking mode: Nat   The running water is too long. Let’s divide it […]

  • Memory management of binder driver


    Memory mapping Before using binder for IPC in user space, the binder driver needs to be initialized. This process mainly performs the open and MMAP operations of binder driver. The memory space used by MMAP mapping binder transport is (1m-8k), but it is only used for virtual address space mapping. The actual physical memory allocation […]

  • How to install Debian on mobile hard disk


    Installing Debian’s grinding pump Microsoft instigating VMware strike In the past two days, I just want to make trouble. I dismantle my dear Ubuntu and install Debian But because of joiningMicrosoft’s insider version I was embarrassed to find that when I opened my VMware Workstation Pro 15 Look at the faceGreen screenTAT,Green screenYou know, orz […]

  • Centos7 uses docker to deploy MSSQL 2017


    MSSQL is the standard configuration of. Net. Generally, people who use. Net basically use MSSQL.In the past, MSSQL could only support Windows platform. Starting from Microsoft’s slogan of embracing open source, the 2017 version of MSSQL began to support Linux system.At the beginning, I installed MSSQL directly in CentOS. Generally speaking, it is much faster […]