evaluating expression 1. shell expansion brace expansion 1 2 3 4 5 a{b,c,d} # ab ac ad a{1..2} #a1,a2 1 a{1..5..2} #a1,a3 parameter expansion 1 2 ${parameter}; $parameter output command 1 2 a = $(cat file ) a = `cat file` other double quote vs single quote, curly bracket, parenthese quote: ‘’: keep word literal meaning “”: expand $,,` 1 2 echo "$(echo hello)" # hello echo '$(echo hello)' # '$(echo hello)'

shell; what’s shell a program which interactive with linux ; list: sh(Bourne shell) bash zsh dash … /bin/sh a linker to a actual shell language 1 !# /bin/sh // a program will run the script 1 echo $0 // the name of the shell language shell basic IFS: input field seperator, default value: space, tab newline define variables export vs not export 1 2 export a=1; # can access in child process a=1; # only access in current process shell type login vs nonlogin

golang 逃逸分析详解 Golang逃逸分析原理剖析 9.5.4 逃逸分析 what: at compile determine if variable escape to heap; why : it will be accessd out of current stack frame, not fittable to allocate in stack when: a variable’s pointer return from func assgin to a data in the heap. 1. closure how how: build ast tree analyse. two invariant: pointer to a stack object cannot outlive that object: variable must be allocated in heap if it’s pointer outlive it

计算机科学速成课40集全 Computer - CPU(Central Processing Unit) Architecture of the central processing unit (CPU) Different Classes of CPU Registers 计算机指令在CPU中的执行过程（图文版） CPU 执行程序的秘密，藏在了这 15 张图里 MIPS_Instruction_Set everything is about caculation what’s program; program = algorithm(function) + data; von noenuman architecture control unit: 包含:progarm counter register, instruction register; 读取和解码指令，执行指令 32bit cpu 能存储 最大内存地址 4g(42ebyte) arithmetic/login unit: 完成实际的计算 register(cache): store data highlight: 程序指令也装进内存里,相比早期写死在控制单元里，具有很大灵活性； instruction 1. type type work component caculate alu jump;call/return alu; control unit(uncontional jump) data transfrom(register and ram, register and register, ram and ram, registr and device) register,ram 2.

Pipeline Syntax ci/cd continuous integration and continuous delivery continuous integration test build continuous delivery deploy jenkins build way freestyle scm 2. build trigger pipeline a set of sh steps pipeline declarative 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 agent any environment { Hello = } stage1 { steps ( sh "cd ~/" sh ''' mkdir abc mv abc cde ''' ) } stage2{ } #finish hook post { always { } success { } failure { } } pipeline script provide more flexible and expressive control over the pipeline

Create custom ESLint rules in 2 minutes rules eslint define a set of rules rules will throw a error or warning when encounter possible problems,stylistic issues 1 2 3 4 5 6 { "rules": { "camelcase": 2, "quotes": [2, "single"], } rules work only you explicitly declare it extend load a set of rules without declaring them plugin a extend of offical rules. To make it work, you should declare or extend it