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See what types of shell interpreters are available on this machine: [root@sanchuang huahsan]# cat /etc/shells /bin/sh /bin/bash /usr/bin/sh /usr/bin/bash /usr/bin/tmux /bin/tmux sh It's a very old interpreter, more than bash Have a sense of history, No bash Easy to use [root@sc ~]# sh switch to sh interpreter sh-4.4# Switch bash to bash inte ...

Virtue wins talent, which is called a gentleman; Talent wins virtue, which is called a villain—— "Zizhi Tongjian · Tang Ji" I Antecedents - reduce duplication of effort Previously, when deploying the running environment of development software in ubuntu, it was necessary to copy and paste the contents in differe ...

I am xuetianyu, an FPGA enthusiast. My research direction is FPGA Architecture Exploration and SOC design. Focus on official account [integrated circuit design course], pull you into "IC design exchange group". 1. Preface It took nearly a week to realize a two-dimensional code recognition alone. In this article, I will introduce in ...

1, Explain In order to continuously update information and manage the ledger (write transactions, query, etc.), the blockchain network has introduced smart contracts to access and control the ledger; Smart contract is called chain code in Fabric, which is the business logic of blockchain application. This article shares how to use the Java ...

1, Judgment: if 1. Single branch mode if Condition test then Command sequence fi if Condition test ; then Command sequence fi Case: [root@localhost jiaofan]# cat b.sh #!/bin/bash if [ -z $1 ] then echo "Error: service name not entered" echo "Usage: script name server name" fi if systemctl is-active $1 &> /dev/null ; then ec ...

1, Bash script set command 1. Introduction Set command is an important part of bash script, but it is often ignored, resulting in problems in the security and maintainability of the script. When bash executes the script, it will create a new Shell. If there is an error in the execution process, bash will ignore the error and continue to e ...

‍ catalogue 1, What is a shell 2, Application scenario of shell script 3, Common shell scripts 4, Summary 1, What is a shell Shell is an application program, which connects users and Linux kernel, so that users can use Linux kernel more efficiently, safely and at low cost. This is the essence of shell. In short, we operate Linux through ...

Logic control - condition judgment 1, Realization of conditional judgment ifcase 2, Simple structure of if if condition ; then Actions performed Actions performed fi 1. Writing of conditions shell command Determine the execution status code of the command [expression] Numeric expressionCharacter expressionFile directory expre ...

Introduction to shell script Absrtact: briefly introduce the knowledge related to shell script, including variables, strings, arrays, operations, functions, script debugging, etc. 1, shell script shell is an application program of Linux system. It starts, pauses, stops the program or controls the computer by accepting the commands en ...

preface Detailed explanation of awk variables, common built-in variables, user-defined variables, built-in variables NR, NF, FNR, RS, ORS, FILENAME, ARGC and ARGV awk variable "Variables" are divided into "built-in variables" and "custom variables". "Input separator FS" and "output separat ...