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Hi!

I'm Viacheslav and I'm very exciting to join to this very interesting backend cours.

I finished first task and I want to share my impression about this before start next one

I got a lot of new information about basics things for Git and I will use these knowledges next times in my work.

I hope, I will finish all tasks in time )))

Best regards!

P.S. Sorry, but I haven't any cats)))


Unix Shell

It was very interesting - to study Unix Shell.

I knew some commands and I had used aliases earlier, but I got more new knowleges after this cours.

I had learnt more new commands and also I had got basic experience with shell scripts

I surely will use a lot of commands in my tasks and also I will apply shell scripts and I want get more info about these powerfull features

There are screenshots below

quiz_01

quiz_02

quiz_03

quiz_04


Git Collaboration

I had studied a little bit interesting course - Udacity Git Collaboration Course and made screenshot after finished.

I repeated some old knowledges and got some new information about collaboration. I didn't know before what does it mean rebase and about difference between fork and clone. And also I understood why we need to set up working with several repositories.

This new knowledges will help my in my work in future.

finis_git_collaboration


NodeJS Basics 1

It was a little bit hard and very interesting.

I learnt a lot new features. I will be use very often array's methods and other powerful practice of JS

I hope next parts and next tasks will be like those..

learnyounode functional-javascript-workshop stream adventure


Memory Management

Answers:

What's going to happen if program reaches maximum limit of stack ?

If program reaches maximum limit of stack (RLIMIT_STACK) we have a stack overflow and the program receives a Segmentation Fault.

What's going to happen if program requests a big (more then 128KB) memory allocation on heap ?

If program requests a big memory allocation on heap (big means more than MMAP_THRESHOLD, which has a default value 128kB), operating system will create such an anonymous mapping instead of using heap memory.

What's the difference between Text and Data memory segments ?

Data memory segments is a memory area with read/write access. This memory area is not anonymous. In this area are held the contents for static variables initialized in source code.

Text memory segments is a memory area with read-only access. This memory area is read-only and stores all of your code in addition to tidbits like string literals. The text segment also maps your binary file in memory, but writes to this area earn your program a Segmentation Fault.

Output of cat /proc/<PID>/maps

561dfddc4000-561dfdec8000 r-xp 00000000 08:05 8657332                    /bin/bash
561dfe0c7000-561dfe0cb000 r--p 00103000 08:05 8657332                    /bin/bash
561dfe0cb000-561dfe0d4000 rw-p 00107000 08:05 8657332                    /bin/bash
561dfe0d4000-561dfe0de000 rw-p 00000000 00:00 0
561dfee6c000-561dfee8d000 rw-p 00000000 00:00 0                          [heap]
7f8c52b3c000-7f8c52f93000 r--p 00000000 08:05 7995513                    /usr/lib/locale/locale-archive
7f8c52f93000-7f8c5317a000 r-xp 00000000 08:05 6296057                    /lib/x86_64-linux-gnu/libc-2.27.so
7f8c5317a000-7f8c5337a000 ---p 001e7000 08:05 6296057                    /lib/x86_64-linux-gnu/libc-2.27.so
7f8c5337a000-7f8c5337e000 r--p 001e7000 08:05 6296057                    /lib/x86_64-linux-gnu/libc-2.27.so
7f8c5337e000-7f8c53380000 rw-p 001eb000 08:05 6296057                    /lib/x86_64-linux-gnu/libc-2.27.so
7f8c53380000-7f8c53384000 rw-p 00000000 00:00 0
7f8c53384000-7f8c53387000 r-xp 00000000 08:05 6296084                    /lib/x86_64-linux-gnu/libdl-2.27.so
7f8c53387000-7f8c53586000 ---p 00003000 08:05 6296084                    /lib/x86_64-linux-gnu/libdl-2.27.so
7f8c53586000-7f8c53587000 r--p 00002000 08:05 6296084                    /lib/x86_64-linux-gnu/libdl-2.27.so
7f8c53587000-7f8c53588000 rw-p 00003000 08:05 6296084                    /lib/x86_64-linux-gnu/libdl-2.27.so
7f8c53588000-7f8c535ad000 r-xp 00000000 08:05 6292953                    /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f8c535ad000-7f8c537ad000 ---p 00025000 08:05 6292953                    /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f8c537ad000-7f8c537b1000 r--p 00025000 08:05 6292953                    /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f8c537b1000-7f8c537b2000 rw-p 00029000 08:05 6292953                    /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f8c537b2000-7f8c537d9000 r-xp 00000000 08:05 6296051                    /lib/x86_64-linux-gnu/ld-2.27.so
7f8c539aa000-7f8c539af000 rw-p 00000000 00:00 0
7f8c539d2000-7f8c539d9000 r--s 00000000 08:05 8396172                    /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
7f8c539d9000-7f8c539da000 r--p 00027000 08:05 6296051                    /lib/x86_64-linux-gnu/ld-2.27.so
7f8c539da000-7f8c539db000 rw-p 00028000 08:05 6296051                    /lib/x86_64-linux-gnu/ld-2.27.so
7f8c539db000-7f8c539dc000 rw-p 00000000 00:00 0
7ffd92794000-7ffd927b5000 rw-p 00000000 00:00 0                          [stack]
7ffd927f9000-7ffd927fc000 r--p 00000000 00:00 0                          [vvar]
7ffd927fc000-7ffd927fe000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]
Heap: 561dfee6c000-561dfee8d000
Stack: 7ffd92794000-7ffd927b5000
MMS: 7f8c52f93000-7f8c53380000

This part of course has more new information for me. I got a performance about a managing of memory by operating system and living a program in memory. It was interesting.


HTTP & HTTPS

It's very simple but very interesting part of course.

Comics and articles are very good for understanding basics but important things about how internet works

Answers:

An evil person can pretend a some www-resource. Your data can be intercept. Also your data or server data can be change. And some browsers can block www-resources if they not use https-protocol.

When data was encrypted by public key, other persons or resources cann't decpryt this data with the same key. Encrypted data can decrypt person or resource who has another key - private, and also, he or she must use another algorithm for read encrypted data.

  • GET: search pet by name - this request don't change any information on server

  • POST: add new pet - this request create new item of pets

  • PUT(POST): change name of an existing pet; add new info about pet's health; assign a pet to a particular doctor in the clinic; register an appointment for a pet; - this requests change information for existing items


SQL Basics

It was simple)))

select.sql

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