Eric Lapouyade Info – Technical stuff and more…

How to install the latest version of Postgresql on Ubuntu

Eric / May 18, 2019

It is quite easy to install the latest version of Postgres on Ubuntu. First, declare Postgres repository, create the file /etc/apt/sources.list.d/pgdg.list like this :

sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" &gt;&gt; /etc/apt/sources.list.d/pgdg.list'

1	sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list'

Import the repository signing key, and update ubuntu package lists

wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update

1 2	wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc \| sudo apt-key add - sudo apt-get update

Then install latest postgresql (actually version 11) and its latest GUI pgadmin (actually version 4) :

sudo apt install postgresql-11 pgadmin4

1	sudo apt install postgresql-11 pgadmin4

Postgresql is now running, you can check that by…

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Uncategorized

rsync two remote hosts

Eric / February 6, 2019

Usually, rsync is used to synchronize one local directory to/from one remote directory. But sometimes, because two hosts cannot see each other directly, one cannot log into one host and rsync to from the other. The solution is to find a third host that can see both hosts and then sync them. Unfortunately, rsync accepts only one remote host. The…

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Uncategorized

How to add existing project to git and configure remote repository

Eric / July 26, 2018

You already started a new project, but it is not under GIT yet. No problem, let’s create a local repository dedicated to your project :

cd your_project_dir
git init
git add .
git commit -m 'first commit'

cd your_project_dir

git init

git add .

git commit -m 'first commit'

Et voilà. Now, in order to have the project available everywhere, you can configure a remote GIT repository. You first have to log into your remote host and configure a new repository :

ssh my_user@my_remote_host
cd all_projects_repo_dir   (or create an empty one)
git init --bare my_project.git

ssh my_user@my_remote_host

cd all_projects_repo_dir (or create an empty one)

git init --bare my_project.git

…

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Git

How to reconcile detached HEAD with master/origin

Eric / April 15, 2018

If you are using pycharm or other IDE, you can easily checkout an older version of your source code, just by right-clicking on the revision you want. Unfortunately, it is not so obvious to go back to the master branch if you do not care about what you are clicking on. Logically, you may have done the same process to…

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Python

Linked items to a Tree

Eric / February 15, 2018

Let’s say you receive a list of 2 linked items having a “is included in” relation. For example, you receive this list :

[('cpqswccmibrev', 'cpqswcc'),
 ('cpqswccfibredevstate', 'cpqswccfibre'),
 ('cpqswccemudev', 'cpqswcc'),
 ('cpqswccmibrevmajor', 'cpqswccmibrev'),
 ('cpqswcc', 'compaq'),
 ('cpqswccmibcondition', 'cpqswccmibrev'),
 ('cpqswccfibredevname', 'cpqswccfibre'),
 ('cpqswccfibre', 'cpqswcc'),
 ('cpqswccfibreeventdescription', 'cpqswccfibre'),
 ('cpqswccmibrevminor', 'cpqswccmibrev'),
 ('cpqswcckzpcc', 'cpqswcc')]

[('cpqswccmibrev', 'cpqswcc'),

('cpqswccfibredevstate', 'cpqswccfibre'),

('cpqswccemudev', 'cpqswcc'),

('cpqswccmibrevmajor', 'cpqswccmibrev'),

('cpqswcc', 'compaq'),

('cpqswccmibcondition', 'cpqswccmibrev'),

('cpqswccfibredevname', 'cpqswccfibre'),

('cpqswccfibre', 'cpqswcc'),

('cpqswccfibreeventdescription', 'cpqswccfibre'),

('cpqswccmibrevminor', 'cpqswccmibrev'),

('cpqswcckzpcc', 'cpqswcc')]

Here (‘cpqswcc’, ‘compaq’) means ‘cpqswcc’ is included in ‘compaq’. You may want to build a relation tree like this :

{   'compaq': {   'cpqswcc': {   'cpqswccemudev': 0,
                                 'cpqswccfibre': {   'cpqswccfibredevname': 0,
                                                     'cpqswccfibredevstate': 0,
                                                     'cpqswccfibreeventdescription': 0},
                                 'cpqswcckzpcc': 0,
                                 'cpqswccmibrev': {   'cpqswccmibcondition': 0,
                                                      'cpqswccmibrevmajor': 0,
                                                      'cpqswccmibrevminor': 0}}}}

{ 'compaq': { 'cpqswcc': { 'cpqswccemudev': 0,

'cpqswccfibre': { 'cpqswccfibredevname': 0,

'cpqswccfibredevstate': 0,

'cpqswccfibreeventdescription': 0},

'cpqswcckzpcc': 0,

'cpqswccmibrev': { 'cpqswccmibcondition': 0,

'cpqswccmibrevmajor': 0,

'cpqswccmibrevminor': 0}}}}

The cool function to do that would be the one in this code :

import pprint
pp = pprint.PrettyPrinter(indent=4)

def isincludedin_to_tree(item_list):
    out = {}
    index = {}
    for k,v in item_list:
        if v not in index and k not in index:
            out[v] = {k: 0}
            index[k] = out[v]
            index[v] = out
        elif v in index and k in index:
            if isinstance(index[v][v],int):
                index[v][v] = { k : index[k][k] }
            else:
                index[v][v][k] = index[k][k]
            to_del = index[k]
            index[k] = index[v][v]
            del to_del[k]
        elif v in index:
            dct = index[v]
            if isinstance(dct[v],int):
                dct[v] = {k: 0}
                index[k] = dct[v]
            else:
                dct[v].update({k: 0})
                index[k] = dct[v]
        else:
            dct = index[k]
            out.update({v:{k:dct[k]}})
            index[v] = out
            index[k] = out[v]
            del out[k]
    return out

in_list = [('cpqswccmibrev', 'cpqswcc'),
 ('cpqswccfibredevstate', 'cpqswccfibre'),
 ('cpqswccemudev', 'cpqswcc'),
 ('cpqswccmibrevmajor', 'cpqswccmibrev'),
 ('cpqswcc', 'compaq'),
 ('cpqswccmibcondition', 'cpqswccmibrev'),
 ('cpqswccfibredevname', 'cpqswccfibre'),
 ('cpqswccfibre', 'cpqswcc'),
 ('cpqswccfibreeventdescription', 'cpqswccfibre'),
 ('cpqswccmibrevminor', 'cpqswccmibrev'),
 ('cpqswcckzpcc', 'cpqswcc')]

out_dict = isincludedin_to_tree(in_list)

pp.pprint(out_dict)

import pprint

pp = pprint.PrettyPrinter(indent=4)

def isincludedin_to_tree(item_list):

out = {}

index = {}

for k,v in item_list:

if v not in index and k not in index:

out[v] = {k: 0}

index[k] = out[v]

index[v] = out

elif v in index and k in index:

if isinstance(index[v][v],int):

index[v][v] = { k : index[k][k] }

else:

index[v][v][k] = index[k][k]

to_del = index[k]

index[k] = index[v][v]

del to_del[k]

elif v in index:

dct = index[v]

if isinstance(dct[v],int):

dct[v] = {k: 0}

index[k] = dct[v]

else:

dct[v].update({k: 0})

index[k] = dct[v]

else:

dct = index[k]

out.update({v:{k:dct[k]}})

index[v] = out

index[k] = out[v]

del out[k]

return out

in_list = [('cpqswccmibrev', 'cpqswcc'),

('cpqswccfibredevstate', 'cpqswccfibre'),

('cpqswccemudev', 'cpqswcc'),

('cpqswccmibrevmajor', 'cpqswccmibrev'),

('cpqswcc', 'compaq'),

('cpqswccmibcondition', 'cpqswccmibrev'),

('cpqswccfibredevname', 'cpqswccfibre'),

('cpqswccfibre', 'cpqswcc'),

('cpqswccfibreeventdescription', 'cpqswccfibre'),

('cpqswccmibrevminor', 'cpqswccmibrev'),

('cpqswcckzpcc', 'cpqswcc')]

out_dict = isincludedin_to_tree(in_list)

pp.pprint(out_dict)

Linux

Install ubuntu 16.04 on a mac book pro in dual boot

Eric / February 5, 2018

Tired to use Mac OS for development purposes, I wanted to install Ubuntu 16.04 in dual boot on my Mac book pro retina 15.6″. For that I needed : A mac book pro with an intel processor A bootable USB stick with ubuntu 16.04 The Disk utility from mac OS The rEFInd boot manager A RJ45 adapter, because Wifi does…

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Linux

‘lnav’ : The log file navigator

Eric / February 1, 2018

You know the following commands : more, grep, tail -f, vi : here is the command that does all that : lnav You can install lnav just by installing the corresponding package :

sudo apt-get install lnav

1	sudo apt-get install lnav

You get a listing which is dynamically refresh like tail -f does. You can search like vi by using / command, you can also filter with…

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Linux

‘htop’ command tool

Eric / February 1, 2018

To monitor running processes, you already know the ‘top’ command, you will get such an output : Now there is the ‘htop’ command which provides much more features and detailed informations : You’ve got colors, text bars graph, commands with arguments : You can scroll up, down AND right and left, and the best : despite it is a text…

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Python

How to get Class attributes order

Eric / January 29, 2018

Before python 3.6 it was difficult to get attributes order from a class. Let’s say, for instance, you want to create a listing class which contains columns to display :

class Column(object):
  pass

class Listing(object):
  col1 = Column()
  col2 = Column()
  col3 = Column()
  col4 = Column()
  col5 = Column()
  col6 = Column()


print( [ k for k in Listing.__dict__.keys() if '__' not in k ] )

class Column(object):

pass

class Listing(object):

col1 = Column()

col2 = Column()

col3 = Column()

col4 = Column()

col5 = Column()

col6 = Column()

print( [ k for k in Listing.__dict__.keys() if '__' not in k ] )

With python 2.7 you will get :

['col6', 'col4', 'col5', 'col2', 'col3', 'col1']

1	['col6', 'col4', 'col5', 'col2', 'col3', 'col1']

With python 3.5 you will get :

['col3', 'col1', 'col4', 'col5', 'col2', 'col6']

1	['col3', 'col1', 'col4', 'col5', 'col2', 'col6']

And finally, with python 3.6, there is no problem any more : attributes…

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Python

How to dynamically create a class with some mixins

Eric / January 24, 2018

Let’s say you want to create a class that includes mixins having names that are known at execution time only, you would do some thing like this :

class_with_mixins = type("my_class_name", tuple(mixins_classes+[BaseClass]), {})

1	class_with_mixins = type("my_class_name", tuple(mixins_classes+[BaseClass]), {})

To get mixins_classes, juste use importlib to get mixins classes from names. A function that would create an instance of such a dynamic class would be something like this :

from importlib import import_module

def get_instance_with_mixins(plugin_class_name,mixins_name,base_class,*args,**kwargs):
    mixins_classes = [ import_module(m) for m in mixins_name ]
    cls = type(plugin_class_name, tuple(mixins_classes+[base_class]), {})
    instance = cls(*args,**kwargs)
    return instance

from importlib import import_module

def get_instance_with_mixins(plugin_class_name,mixins_name,base_class,*args,**kwargs):

mixins_classes = [ import_module(m) for m in mixins_name ]

cls = type(plugin_class_name, tuple(mixins_classes+[base_class]), {})

instance = cls(*args,**kwargs)

return instance

…

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