A quick way to comment/uncomment lines in vim:

Put your cursor on the first # character, press Ctrl+V, and go down until the last commented line and press x, that will delete all the # characters vertically.


For commenting a block of text is almost the same:

- First, go to the first line you want to comment, press Ctrl+V. This will put the editor in the VISUAL BLOCK mode.

- Then using the arrow key and select until the last line.

- Now press Shift+I, which will put the editor in INSERT mode and then press #. This will add a hash to the first line.

- Then press Esc (give it a second), and it will insert a # character on all other selected lines.

#vim #comment #comment_out #visual_block

Stay tuned for the Django video tutorials for the weekend. Yay!!!

Happy coding ✌💥💫

این رازِ پُر از عذاب پیشت باشد
تصویر من خراب پیشت باشد

شاید که اربعینت نبودم آقا !
این اشک علی الحساب پیشت باشد
😭😭😭😭

سائلم ؛ آب و دانه میخواهم
رحمت" مادرانه" میخواهم

آی "بی بی" گدا نمیخواهی!؟
پسر بی وفا نمیخواهی!؟😭😭😭

کاش میشد ز من سوال کنی
پسرم کربلا نمیخواهی!؟

پسر بی وفا نمیخواهی 😭😭😭

Routes implementation in `Django` and how to wire routes & views

#python #django #route #view #django_part8

In ls you can list files by using regex pattern as below:

ls data.subtitle_*

* is gready and list all the files that start with data.subtitle_.

Now lets say you want to get count of files which is listed by ls command. For that you can use wc -l as follow:

ls data.subtitle_* | wc -l

Now you shoud the count of files listed by the first command. This method of using 2 commands is piping commands, which is in fact separated by | (pipe)

#linux #sysadmin #ls #wc #command #bash #terminal

tr command in Linux can be used to trim special characters from a string in bash script. Let's say we want to remove underscore (_) from the string _hello_:

$ echo "_hello_" | tr -d "_"
 hello

As you can see the output is hello.

-d flag causes to delete _ from the whole string.

In case you want to delete multiple special characters, that's easy as pie:

$ echo "_sal-am_" | tr -d "_-"
 salam

We have removed - and _ from the string above.

Making lower case to uppercase:

tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ
 asdasd
 ASDASD

OR:

tr [:lower:] [:upper:]
 asdasd
 ASDASD

Turn {} into ():

$ echo '{hello}' | tr '{}' '()'
 (hello)

#linux #tr #translate #trim #bash #sysadmin

Preventing installation of devDependencies node modules:

npm install in the package directory installs the dependencies in the local node_modules folder.

In global mode (ie, with -g or --global appended to the command), it installs the current package context (ie, the current working directory) as a global package.

By default, npm install will install all modules listed as dependencies in package.json.

With the --production flag (or when the NODE_ENV environment variable is set to production`), `npm will not install modules listed in devDependencies.

#node #npm #package_json #devDependencies #NODE_ENV

#ebook #epub #git

Use jq to process JSON in linux terminal. In order to parse JSON in linux you can use sed, awk and grep, but with jq it is far more easier.

https://stedolan.github.io/jq/

#jq #json #terminal #linux #sysadmin

Play around with jq in live mode by using the site below:

https://jqplay.org/

#jqplay

Did you know that you can apply len python function on your classes? Let's say you have a Lessons class and when a use use len() function on your class it should return number of lessons inside of your class. For our sample let's say we have the below class:

class Lessons(object):
     def __init__(self, lessons=0):
         self.lessons = lessons

     def insert(self, data):
         # let's assume we have save data in database
         self.lessons += 1

     def __len__(self):
         return self.lessons

This is a simple class that sets a fake lesson in your class and insert a new lesson.

std_lessons = Lessons(1)
 print len(std_lessons) # output: 1

 std_lessons.insert({})
 print len(std_lessons) # output: 2

As you can see above we have used len on our class itself. In case you don't implemet __len__ on your class and use len() on it, there will be an AttributeError:

len(std_no_len)
 Traceback (most recent call last):
   File "<input>", line 1, in <module>
 AttributeError: Lessons instance has no attribute '__len__'

__len__ is built-in class and can be implemented in different scenarios. There are tons of built-in functions that you can master and use to improve code quality and prove that you are professional.

#python #class #builtin #len #__len__

#ebook #epub #python

Did you know that the most easiest way to start a simple HTTP server using python is just a command?

$ python -m SimpleHTTPServer
 Serving HTTP on 0.0.0.0 port 8000 ...

SimpleHTTPServer is a python module that serve all the data that is present inside of the current directory. Install this package and enjoying playing around :)

#python #SimpleHTTPServer #server

Sometimes to know your IP address, you have to open a web browser and open a site that gives you the ip address of your system. But what if you are a sysadmin and you don't have access to a browser on Linux server? What if you don't wanna leave your terminal?

Get your IP address from command line using curl:

$ curl ifconfig.co
 80.171.524.14

#linux #sysadmin #curl #ifconfig #ip #ip_address #ipv4

In order to extract only text from an HTML website in the most robust way without using regex or urlib or so, use the python library below:

https://github.com/aaronsw/html2text

Usage in terminal is:

Usage: html2text.py [(filename|url) [encoding]]

If you want it to use inside of your python code:

import html2text
 print html2text.html2text("<p>Hello, world.</p>")

#python #html2text #github #html #text

More about jinja2:

If you want to set a variable named button:

{% set button = 'Login' %}

If you want to include a partial template (child template) into your parent template use include:

{% include 'fa.button.tpl' %}

BE CAREFUL that we have used {% NOT {{ for the code block.

If one of your templates inherits from a main layout use extends directive:

{% extends "layout.tpl" %}

#python #jinja2 #extends #include #set #variable #set_variable #layout

In python when you open a file using open command the your can read the content of the file. read will read the whole content of the file at once, while readline reads the content of the file line by line.

NOTE: if file is huge, read() is definitely a bad idea, as it loads (without size parameter), whole file into memory.

NOTE: it is good practice to use the with keyword when dealing with file objects. The advantage is that the file is properly closed after its suite finishes, even if an exception is raised at some point. (We have reviewed with in depth a couple days ago)

NOTE: read function gets a size parameter that specifies the chunks read from a file. If the end of the file has been reached, f.read() will return an empty string.

For reading lines from a file, you can loop over the file object. This is memory efficient, fast, and leads to simple code:

>>>
 >>> for line in f:
 ...     print(line, end='')
 ...
 This is the first line of the file.
 Second line of the file

#python #file #read #readline #efficiency

In case you have missed with tutorial read this post, which is related to the previous post.