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Permission management in Linux 1, Authority overview 1. Basic concepts of permissions In the management of multi-user computer system, permission refers to that a specific user has a specific right to use system resources. In Linux, you have read, write and execute permissions respectively: Permissions for filesPermissions for directoryRea ...

prefaceIn this small room with only cangls and Xiaobai, there was a discussion on learning methods.Xiaobai: cangls, I want to ask you a question. How do you remember so many linux commands.cangls: I, others watch my little movies. I don't know! Maybe there are too many examples, just remember some.The inspiration for this writing comes from a b ...

Introduction to interprocess communication Purpose of interprocess communication Data transfer: one process needs to send its data to another processResource sharing: multiple processes share the same resources.Notification event: a process needs to send a message to another process or group of processes to notify it (them) of an event ...

1, Concept of index An index is a sorted list in which the index value and the physical address of the row containing the data containing the value are stored (similar to the linked list of C language, which points to the memory address of the data record through a pointer). After using the index, you can not scan the whole table to locat ...

#1. Significance of users and user groups# 1) The significance of users' existence and system resources are limited. How to reasonably allocate system resources? In solving this problem, we must have the cooperation of multiple resources 1. Identity account 2. Authorize author 3. Certification auth 3A mechanism, which constitutes the lowe ...

Shell variable Use a fixed string to represent unfixed content Type of variable Custom variable Defining variables: variable name = variable value. Variable names must start with letters or underscores and are case sensitive (example: ip1=192.168.2.115)Reference variable: $variable name or ${variable name}View variables: echo $vari ...

Introduction to powermt command PowerPath integrates multi-path I/O, automatic load balancing, and path failover to make storage management easier. This paper summarizes the use methods and precautions of common PowerPath commands, and provides a reference for host system administrators to configure, view, delete, save and restore HbAS / paths ...

1, Overview 1. Concept 1) What is a shell: shell It is a command interpreter, which is at the outermost layer of the operating system. It is responsible for directly talking with the user, interpreting the user's input to the operating system, processing various operating system output results, and outputting them to the screen for feedb ...

An openSSH server 1. Introduction to ssh protocol ssh Protocol is a secure channel protocol, which encrypts the communication data for remote management 2,openSSH Service Name: sshd Server main program:/usr/sbin/sshd Server configuration file:/etc/ssh/sshd_config 2, Configure OpenSSH server 1,sshd_ Common options for config configura ...

Distributed storage Ceph 1: Classification of storage 1. Local file system ntfs(windows),ext2,ext3,ext4,xfs ext2 does not have logs, 3 and 4 have logs: the log function of the file system (to prevent the machine from suddenly powering down): all data will be saved in the log of the file system before saving data to the disk, so as to preven ...