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How to give better examples

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Rails free hosting

If you want free hosting, I mean free, not-cheap or other kinds of hosting. The only option which I know for now is Heroku.

There are some websites which advertise them as free rails hosting but they are paid.

So stay safe with the good old, slow on boot but very stable and enjoyable to work Heroku!

Akonadi KDE

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Make tables visible on postgres after pgloader

Hello folks,

You have just used the pgloader to import some database in postgres but when you do

space_util=# \dt
Did not find any relations.

The problem is that you have to fix the search path for your tables.

Here is how to do it (or check the link for more ways)

space_util=# ALTER DATABASE space_util SET search_path = space_util,public;
space_util=# \dt
                                    List of relations
   Schema   |                           Name                           | Type  |  Owner   
------------+----------------------------------------------------------+-------+----------
 space_util | some_nice_table | table | postgres

How s3fs caching

…or one-day just to add one line of code

s3fs.S3FileSystem.cachable = False

Adding caching under the good and not mentioning it in the documentation – that is called a dirty trick.

My case was lambda processing s3 files. When a file comes on s3 lambda process the file and triggers next lambda. The next lambda works fine only the first time.

The first lambda is using only boto3 and there is no problem.

The second lambda use s3fs.

The second invocation of the lambda is using already initialized context and the s3fs thinks that it knows what objects are on s3 but it is wrong!

So…. I found this issue – thank you jalpes196 !

Another way is to invalidate the cache…

from s3fs.core import S3FileSystem


S3FileSystem.clear_instance_cache()
s3 = S3FileSystem(anon=False)
s3.invalidate_cache()

Daily systemd commands

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Why one should use Firefox in 2020

I have switched from Google Chrome to chromium for security and privacy issues. Now I am switching from Chromium to Firefox because of many issues.

Chromium stopped to ship deb packages and start using Snapd. Snap runs in cgroup (probably) and hides very important folders from the OS

  • /tmp
  • ~/.ssh

Certificates
My access to some payment website was rejected because the certificates are in the ~/.ssh

System tmp
When I download some junk files/attachments I store them in the /tmp folder and on the next system reboot, my /tmp is cleaned. When I can’t access the /tmp from Chrome I have started using ~/tmp/ and have tons of useless files.

Speed
When I switch to firefox I noticed that this browser is much faster than Chrome.

Chromuim after migrating to snapd do not work correctly with dbus

Firefox is faster

No easy way to add a custom search engine.

Sort AWS S3 keys by size

A naive version which will sort the keys in a s3 folder. It would not work if the keys contain spaces.

Here is a usage example

aws s3 ls BUCKETNAME/signals/wifi/  |  ~/bin/aws-s3-sort.rb
#!/usr/bin/ruby
content = ARGF.read

lines = content.split("\n")

key_size = {}
lines.each do |line|
  cells = line.split(' ')
  key_size[cells[2]] = cells[3]
end; ''

sorted = key_size.sort_by { |k, v| k.to_i }.to_h

sorted.each do |key, value|
  puts "#{key} -> #{value}"
end; ''

Extract a huge number of files from AWS s3 glacier

…or how to run multiple commands in parallel

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Dynamodb Table Export and local Import

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