hochun836

// data
{
    "_id" : ObjectId("5f4f03709f80fb9179d5136e"),
    "data1" : 1.0,
    "data2" : 2.0,
    "data3" : 3.0,
    "data4" : 4.0,
    "data5" : 5.0,
    "other" : {
        "data6" : 6.0,

hochun836

---
>php --version
PHP 7.4.16 (cli) (built: Mar  2 2021 14:06:15) ( ZTS Visual C++ 2017 x64 )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies

>composer --version
Composer version 2.2.5 2022-01-21 17:25:52
---

hochun836

# base
key in 'cmd' in the address of file explorer to open cmd
ctrl + left click to open new window

# hotkey
esc // clear input

# common
C: // go to C drive
D: // go to D drive

hochun836

# base
fileName is case-sensitive
command is also case-sensitive
program is a file
process is running in memory by executing the program
absolute path starts with / (this / means the root directory)

# hotkey
ctrl + a // move cursor to begin
ctrl + e // move cursor to end

hochun836

# hdfs
hdfs version
hdfs namenode -format // IMPORTANT: format the DFS filesystem

# hadoop
hadoop fs -ls <dfs-path>
hadoop fs -cat <dfs-path>
hadoop fs -get <dfs-path>
hadoop fs -put <local-path> <dfs-path>
hadoop fs -mkdir <dfs-path>

hochun836

# docker desktop
docker toolbox // win7
docker desktop for windows // win10 (include linux container & window container)
docker desktop for mac
=> ref: https://skychang.github.io/2017/01/06/Docker-Docker_for_Windows_10_First/

Q: can windows containers be hosted on linux?
A: no
=> ref: https://stackoverflow.com/questions/42158596/can-windows-containers-be-hosted-on-linux

hochun836

=====================================
pseudo distribution
=====================================

# hadoop-env.sh
export JAVA_HOME=/home/hadoop/app/java

# core-site.xml
<configuration>
    <property>

hochun836

# spark-env.sh
export SPARK_DIST_CLASSPATH=$(hadoop classpath)

hochun836

# base
mysql --help
mysql // user: root, host: localhost
mysql -u <user> [-p] [password]
mysql -u <user> [-h] [host]

# mysql shell
## common
status;
select version();

hochun836

# bash command
vim // open a blank file
vim <file-path> // open a file (if no exist, when :w will create)
vim <file-path> +<line-number> // open a file and go to assigned line number
vim . // open the current directory and select file

# command mode (default mode)
: // switch to ex mode
i // insert, switch to insert mode
a // append, switch to insert mode