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1. Introduction to shell 1. Configuration requirements: OS: RHEL7 or CentOS8 is recommended CentOS8 will stop maintenance at the end of 2021 RHEL8 or dragon lizard operating system https://openanolis.cn 2. Classification of Shell Scripting Language There are two kinds of shells: Bourne shell and C shell Bourne shell includes Bourne s ...

Apache Kafka is an open-source distributed event streaming platform used by thousands of companies for high-performance data pipelines, streaming analytics, data integration, and mission-critical applications. 1 Overview 1.1 basic concepts 1.1.1 Topic By classifying messages through Topic mechanism, we can think that each Topic is a queue ...

Author: michelangela Yang Engineers who pursue technology are generally addicted to cleanliness, especially in the cloud native world. Although Kubernetes has formulated the container runtime interface (CRI) standard, in the early stage, only Docker can be used when the container runs, and Docker does not adapt to this standard, so it opened ...

Judge by document type Test options Test optionseffect-bJudge whether the file exists and whether it is a block device file (yes, the block device file is true)-cJudge whether the file exists and whether it is a character device file.-dJudge whether the file exists and whether it is used as a directory file.-eDetermine whether the file ex ...

Due to the needs of work and business, the author has developed a set of freshman enrollment identity verification system, which is used to verify the identity of Freshmen in real time when they enter school (the Ministry of education requires freshmen to conduct face comparison when they enter school), and count the check-in situation of Fresh ...

preparation Start hadoop cluster [amelia@hadoop102 hadoop-2.7.2]$ sbin/start-dfs.sh -help: output this command parameter [amelia@hadoop102 hadoop-2.7.2]$ hadoop fs -help rm Create / sanguo folder [amelia@hadoop102 hadoop-2.7.2]$ hadoop fs -mkdir /sanguo Check whether the sanguo file exists in hadoop 2. Upload -moveFromLocal: cut and ...

Text 3: swordsman and find wildcard Match file name *: Match 0 or more characters ?: Match any character [list]: matching list Any single character in [c1-c2]: matching c1-c2 Any single character in [^c1-c2]/[!c1-c2]: Mismatch c1-c2 Any character in {string1,string2,...}: matching{}Any single string in find file lookup Complete the file s ...

Fundamentals of shell programming (shell script learning notes) loop In Shell programming, it is often necessary to repeatedly execute one or a group of commands, such as printing 10 "Hello World" continuously - although writing 10 echo "Hello World" instead of loop can also complete the same work, but what if printi ...

The following shell commands are gitbash installed on windows can execute successfully. The single and double quotation marks under linux may be different. Common basic commands Commands: let let command is a tool for calculation in BASH, which is used to execute one or more expressions. It is not necessary to add $to represent vari ...

1. Definition of variables A variable is the address of an area of memory Meaning of variables The command cannot manipulate the value that changes all the time. Using a fixed string of characters to represent an unfixed target can solve this problem 2. Variable definition method in shell script Environment level: the variable becomes invalid a ...