Find files between specific times using find

Problem

You would like to find the files modified between certain times using find

Solution

Use the following find command using the -newerXY parameter to specify times you want to look for (ie betwen 2019-09-23 06:00:00 and 2019-09-23 10:00:00)

find . -type f -newermt "2019-09-23 06:00:00" ! -newermt "2019-09-23 10:00:00" | xargs ls -tral

Setup your own gitlab runner

To add your own gitlab runner, follow the steps below

  • Create your runner, in EC2, Google, or any other cloud provider and have ssh access to it.
  • Login to your runner from the previous step and install the gitlab-runner (there are various methods described here: https://docs.gitlab.com/runner/install/. We install using Gitlab’s repositories)
  • Register the gitlab-runner by following the instructions here: https://docs.gitlab.com/runner/register/index.html . You would need to get the token for each project you want to register your runner with (Gitlab -> Settings -> CI/CD -> Runners -> Expand). You can use different executors for your running during the registration such as docker, shell etc.
  • Go to your Gitlab project and find the runner you register above and enable it for the project. You should also add the tags: name_of_your_runner in your .gitlab-ci.yml file.

Cannot login to MariaDB server with root account

Problem

You are trying to login to MariaDB with the root user, but even after resetting the password, it is still not possible to login.

Solution

It seems that certain MariaDB packages that come with Linux distributions use the unix_socket as the authentication method.

MariaDB [mysql]> SELECT user, host, plugin FROM user WHERE user='root';
+------+-----------+-------------+
| user | host      | plugin      |
+------+-----------+-------------+
| root | localhost | unix_socket |
+------+-----------+-------------+
1 row in set (0.00 sec)

Change the plugin as described here (https://stackoverflow.com/a/43424234) with the following:

MariaDB [mysql]> UPDATE mysql.user SET plugin = '' WHERE user = 'root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Change PDF orientation in linux command line

Problem

You would like to change the orientation of a PDF file (portrait to landscape) in the linux command line

Solution

Use the pdftk program as following (taken from the answer https://unix.stackexchange.com/a/394068)

pdftk portrait.pdfcat 1-endwest output landscape_anti_clockwise.pdf

pdftk portrait.pdf cat 1-endeast output landscape_clockwise.pdf

Error installing json 1.8.3 with ruby 2.4

Problem

You are trying to install the gems for your rails application in a new computer, or by using ruby 2.4 and you get the following error:

Solution

Remove your old Gemfile.lock file and run bundle again. A newer version of json (ie 1.8.6) should be installed.

Routing rspec with nested routes

Problem

You would like to add a routing rspec test in your rails application that tests for a nested route.
So while you have something like the following in your config/routes.rb file:

you want to add the following test for your route:

but you are getting an error like the following:

Solution

You will need to change your rspec to the following using any number for the user_id:

Solution adapted from here

ActiveRecord::InvalidForeignKey: PG::ForeignKeyViolation: ERROR: …

Problem

You have a Ruby on Rails application/engine with some tests in Minitest and using postgresql as the db. In the original development environment all the tests that use fixtures and foreign key validations pass, but when you try to move to a different environment with new database some or all of you tests fail with a message that refers to the ForeignKeyViolation as in:

Solution

Since active record disables the foreign keys before loading the fixtures in the database, the user that you run the tests with needs to have superuser permissions in the test database. Otherwise the fixtures are not loaded. So add the superuser permissions to your user:

You may need to drop and create your test database.

Running a specific Cop in Rubocop

Problem

You are working on an existing rails project with many rubocop warnings and you would like to fix certain types or warnings by getting only the specified files.

Solution

So for example when you use rubocop you first get the following for all the files in the project:

You can get a grouping of the errors by using the following:

If you would like to know only the files for a certain type of warning to be able to fix them you could try the following:

Using Array.wrap in Rails when the results could either be a string or an array

Problem

You want to use some array method in a value returned, which can either be a single value or an array of values.

Solution

Rails ActiveSupport Array, provides a method called wrap, that can be used to:

Wraps its argument in an array unless it is already an array (or array-like)

Full explanation of the method here.

Thanks Miles

SSL received a record that exceeded the maximum permissible length.

Problem

You want to install rbenv, but when you are trying to clone the code with:

you get the following error:

Solution

If you are behind a proxy server make sure that you add your proxy server details in your ~/.bash_profile and source the file afterwards.

So first add the details of your proxy like:

And finally source the file before running the installation again: