#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.

One of the benefits of Django`'s `QuerySet is that you can apply filters on it, slice it and move it around your classes without actually hitting the database until you do so.

One of the ways that executes the query is using iteration:

for c in Course.objects.all():
     print(c.title)

NOTE: the first time you iterate over the query, it hits the database and get the result NOT in each iteration.

In the below ways your query will be evaluated (executed):
- repr
- len
- list (e.g.: `list(Entry.objects.all())`)
- bool

#python #django #querySet #query_set #evaluation

If you are using python 3.5 or greater and want to merge to dictionaries:

>>> a = {'a': 1}
 >>> b = {'b': 2}
 >>> {**a, **b}
 {'a': 1, 'b': 2}

That's it! You have merged 2 dictionaries in the most simplest way ever. :)

If you are using python 2.7 or python 3.4 or less, merge dictionaries as below:

def merge_two_dicts(a, b):
     c = a.copy()
     c.update(b)
     return c

python #python3 #merge #dictionary

In normal git flow in case you have to checkout a file you would use:

git checkout -- your_file_name

In case you want to checkout multiple files you give other file names in front of checkout --. Sometimes there are bunch of modified files that you want to checkout all of them at once, so you need to go to the root of the project and:

git checkout -- .

It will checkout all files in your project.

You can also use:

git reset --hard

It will reset your working directory and replace all changes (including the index).

#git #checkout #reset #hard

If you want to comment a block of code out in Jinja2 template, use {# ... #}. It can also span into multiple lines:

{#
      <tr class="">
          <td colspan="2" style="font-family:Ubuntu,Helvetica,Arial,sans-serif; padding: 0px 0px 0px 20px;" class="">
              Regards,
          </td>
      </tr>
      <tr class="">
          <td colspan="2" style="font-family:Ubuntu,Helvetica,Arial,sans-serif; padding: 0px 0px 30px 20px;" class="">
              SYSTEM INFO
          </td>
      </tr>
 #}

#python #jinja2 #comment #comment_out

It has been set to my routine task to copy folder/files from my local host or a remote linux server to another server or vise versa. scp linux command is used for this specific need.
The general command is:

scp YOUR_LOCAL_FILE USERNAME@YOUR_SERVER:~

The above command will copy a file from your local machine to a remote server. If you want to copy a folder to a remote machine user -r to recursively copy the whole folder into the remote.

You can also copy from your remote server to your local machine by changing the order in scp as below:

scp USERNAME@YOUR_SERVER:~/YOUR_REMOTE_FILE .

The above command will copy the remote file called YOUR_REMOTE_FILE from the home directory to your current path (.). Instead of dot you can provide your full path.

NOTE: use man scp and see tons of flags to master this command.

#linux #sysadmin #scp #copy

https://www.codementor.io/garethdwyer/building-a-telegram-bot-using-python-part-1-goi5fncay

#python #telegram #bot #token #botfather

jinja2 has tons of filters for strings, lists, etc that can be used to make the process of, um well, filtering simpler.

To apply a filter you can use pipe symbol (|). In order to lower case`/`upper case a string:

{{"SOMETHING"|lower}}
 {{"sOmThing"|upper}}

Or let's say getting the max number from a list:

{{ [1, 2, 3]|max }}

The filters are endless, see below for more:

https://jinja.pocoo.org/docs/2.10/templates/#filters

#python #jinja2 #template #filter #uppercase #lowercase #max

📺 نسخه جدید تلگرام با امکانات جذابی مانند ارسال مجموعه عکس، فیلم به صورت یک مطلب و pin کردن پیام در کانال و... منتشر شد.
@Farsna

For enabling push notification on pushd server, you need to get a file with .p12 extension and .cer certificate file. For pushd to work you need to generate a .pem file and give its path in push configuration(`/etc/pushd/pushd.conf`).

We need to generate 2 pem files one called apns-cert.pem (generated from .cer file) and the other called apns-key.pem (generated from .p12 file).

To generate .pem file use openssl command, with the format below:

openssl pkcs12 -in YOUR_KEY.p12 -out apns-key.pem -nodes

NOTE: it may ask you for the password, enter the given password by whom that gave you the p12 file.

-in set your input file name and -out sets your output file name which will be generated.

And now generate the key pem file:

openssl x509 -in cert.cer -inform DER -outform PEM -out apns-cert.pem

Restart the pushd and check for any error in /var/log/pushd.

#pushd #openssl #p12 #cer #pem #push