aleksey_dev_grin

PostgreSQL / helpful commands

2022-05-21T09:06:59.526Z

To know version

SELECT version(); #From PostgreSQL

psql -V #From bash

HELP!

psql --help

To describe a table such as a column, type, modifiers of columns, etc., you use the following command:

\d table_name

List available schema

To list all schemas of the currently connected database, you use the \dn command.

\dn

List available functions

To list available functions in the current database, you use the \df command.

\df

Quit psql

To quit psql, you use \q command and press enter to exit psql.

\q

User

to list all user accounts (or roles) in the current PostgreSQL database

\du

Database

List available databases

\l

List available tables

\dt

Connect co another DB

\c database_name

\connect databese_name

To create a new database:

CREATE DATABASE lusiadas;

To create a database sales owned by user salesapp with a default tablespace of salesspace:

CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

Create database:

CREATE USER jonathan;

Create a user with a password:

CREATE USER davide WITH PASSWORD 'jw8s0F4';

Create a user with a password that is valid until the end of 2004. After one second has ticked in 2005, the password is no longer valid.

CREATE USER miriam WITH PASSWORD 'jw8s0F4' VALID UNTIL '2005-01-01';

Create an account where the user can create databases:

CREATE USER manuel WITH PASSWORD 'jw8s0F4' CREATEDB;

User

Create a user with no password:

CREATE USER jonathan;

Create a user with a password:

CREATE USER davide WITH PASSWORD 'jw8s0F4';

Create a user with a password that is valid until the end of 2004. After one second has ticked in 2005, the password is no longer valid.

CREATE USER miriam WITH PASSWORD 'jw8s0F4' VALID UNTIL '2005-01-01';

Create an account where the user can create databases:

CREATE USER manuel WITH PASSWORD 'jw8s0F4' CREATEDB;

Midnight Commander + Mac OS

2022-05-02T09:18:11.706Z

How to install Midnight Commander on Mac OS?

It turned out to be unimaginably easy.

Start Terminal
Install Home Brew
Install Midnight Commander:

brew install mc

4. Done!

Docker

2022-04-28T13:26:11.062Z

docker –version

docker pull <image name> # This command is used to pull images from the docker

docker run -it -d <image name> </br> # This command is used to create a container from an image

docker ps # This command is used to list the running containers

docker ps -a # This command is used to show all the running and exited containers

docker exec -it <container id> bash # This command is used to access the running container

docker stop

docker kill

docker commit

docker login

docker push

docker images

docker rm

docker rmi

docker build

List of the images

docker image

List of the started containers

docker ps

List of all containers (include stoped)

docker ps

Sample Dockerfile for Java

FROM openjdk:8-jdk-alpine

JAR_FILE=target/*.jar

COPY ${JAR_FILE} app.jar

ENTRYPOINT ["java","-jar","/app.jar"]

Git // tips

2022-04-20T08:11:52.019Z

Remove existing files from the repository:

find . -name .DS_Store -print0 | xargs -0 git rm -f --ignore-unmatch

Add this line:

.DS_Store

to the file .gitignore, which can be found at the top level of your repository (or create the file if it isn't there already). You can do this easily with this command in the top directory:

echo .DS_Store >> .gitignore

Then commit the file to the repo:

git add .gitignore
git commit -m '.DS_Store banished!'

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Branches

Git branch listing

git branch -a #all local and remote branches are listed git branch -r #remote branches are listed git branch #only local branches are listed

Create new git branch with switching to this branch

$ git checkout -b <branch-name>

Create new git branch without switching

$ git branch <branch_name>

Switch between branches

$ git checkout <branch_name>

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git rm

The "rm" command helps you to remove files from a Git repository. It allows you to not only delete a file from the repository, but also - if you wish - from the filesystem.

Deleting a file from the filesystem can of course easily be done in many other applications, e.g. a text editor, IDE or file browser. But deleting the file from the actual Git repository is a separate task, for which git rm was made.

Important Options

<filename>

The name of a file (or multiple files) you want to remove. Naming the file you want to remove can be as simple as providing the filename / path to a single file. But you can also provide multiple filenames (delimited by spaces) or even a wildcard pattern (e.g. test.*).

--cached

Removes the file only from the Git repository, but not from the filesystem. By default, the git rm command deletes files both from the Git repository as well as the filesystem. Using the --cached flag, the actual file on disk will not be deleted.

`-r`

Recursively removes folders. When a path to a directory is specified, the -r flag allows Git to remove that folder including all its contents.

--dry-run

No files are actually removed. With this option (or its shorthand -n notation), you will only see an output of the files that Git would remove - but no files are actually deleted.

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.gitignore

Maven

2022-04-15T14:32:00.346Z

Top Commands

Creating a maven standalone project

mvn archetype:generate -DgroupId=org.cloudhadoop -DartifactId=myproject

Creating a web standalone project

mvn archetype:generate   -DarchetypeGroupId=org.apache.maven.archetypes    
-DarchetypeArtifactId=maven-archetype-webapp   -DgroupId=com.cloudhadoop    
-DartifactId=mywebapp

To clean a java project with maven

mvn clean

Compile maven project

mvn compile

To run the maven by skipping unit and integration tests

mvn clean install -Dmaven.test.skip=true or   
mvn clean install -DskipTests=true  

or with a package goal
```markup
mvn package –DskipTests or  
mvn package -Dmaven.test.skip

Debug Maven

mvn -X
mvn dependency:tree
mvn dependency:resolve
mvn dependency:resolve -Dartifact=groupId:artifactId:version

mvn help:effective-pom

Super POM - Simplest POM - Effective POM

Super POM is

location:

Simplest POM is

location:

Effective POM is a mixture of Super POM and Simplest POM. It's better to say that the Effective POM is actual POM that your project uses.

mvn help:effective-pom

location:

Maven dependencies and transitive dependencies

Dependencies are just dependencies that you literally use, including in your Simplest POM.

Transitive dependencies are hidden from you. Because you use them using explicit dependencies.

mvn dependency:resolve // link

Goal that resolves the project dependencies from the repository. When using this goal while running on Java 9 the module names will be visible as well.

mvn dependency:tree // link

Displays the dependency tree for this project. Multiple formats are supported: text (by default), but also DOT, GraphML, and TGF.

mvn dependency:analyze // link

Analyzes the dependencies of this project and determines which are: used and declared; used and undeclared; unused and declared.

How to exclude transitive dependency?

FE: Dependency org.apache.velocity includes transitive dependency oro.

To exclude you have to write <exclusions> tags in your Simplest POM:

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <exclusions>
            <exclusion>
                <groupId>oro</groupId>
                <artifactId>oro</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

Plugins

Official Apache documentation.

Maven Build Lifecycles

Official Apache documentation.

Maven Packaging Types / JAR - WAR - EAR - ...

msi
rpm
tar
tar.bz2
tar.gz
tbz
zip

IndelliJ Idea Hot Keys for Maven

Show Dependencies...//⌥⇧⌘U //

Show Dependencies Popup// ⌥⌘U //

Load Maven changes // ⇧⌘I // Ctrl+Shift+O

Maven - WTF?

2022-04-14T15:46:14.236Z

How to set on MacOS?

1.1. Go to Oracle download and install JDK (better latest version)

1.2. Go to Apache download and unpack Apache Maven

1.3. Start Terminal and execute /usr/libexec/java_home

1.4. Copy path. It will needs after some issues. Path name will be like this: /Library/Java/JavaVirtualMachines/jdk-18.jdk/Contents/Home

1.5. Guide for the all types of MacOS

Creating new Spring MVC project

2022-01-15T11:09:07.954Z

1) New Maven project

2) Add Maven archetype webapp

3) git init

4) Create repository on GitHub.com

5) make command from GitHub

6) Download Apache Tomcat server from https://tomcat.apache.org/ (.zip file)

7) Unzip file

8) Run -> Edit configuration ->

9) Ok -> Restart InlelliJ IDEA

10) Run -> Tomcat

11) If "apache tomcat error=13 permission denied" then

chmod a+x /path/to/tomcat/bin/catalina.sh

12) git add .

13) git commit -m 'run server'

14) git push

15) Add dependences to pom.xml

https://mvnrepository.com/

— Spring Core

— Spring Context

— Spring WEB

— Spring WEBMVC

— Thymeleaf - Spring5

Жадница

2021-12-26T13:27:08.282Z

Сын обозвал дочь. Он это выразил случайно, но получилась законченная мысль и более ем

Утренний высер.

2021-12-21T06:22:21.279Z

Он полезный самый.

Программирование - это начало программирования

2021-11-26T11:13:41.519Z

Оказалось, что программирование - это только начало программирования.

Понятно, что любое ремесло, которое нацелено на выдачу конкретного результата требует времени и сил. Но когда не знаком предметной областью, то некоторые аспекты становятся настоящими открытиями.

После того как поднял все циклы, алгоритмы, конструкции (кроме бинарных деревьев), мьютексы, стримы и прочую плюшки было удивительно узнать, что в чистом видео - это просто "блестяшка". Это как навык шить у хирурга, как умение читать ЭКГ у функционального диагноста... ТЕ это обретает смысл, только в комплексе плана лечения пациента (в чем бы оно не заключалось). В медицине - это звучит о***нно: Клиническое мышление.

Так и программировании. Просто писать код - это супер, шарить в алгоритмах - тоже пруф. Но это все еще должно лечь в Архитектурные паттерны (звучит как "разработка протонных двигателей", ТЕ тоже мегапафосно). И без этого навыка ты не программист и нахер никому не нужен.

#solid

#clrs