Indian Railways Railway Signal Engineer Interview Questions and Answers

The docker ps command is used to list all the running containers on a Docker host.

• It provides information about the container ID, image used, command being run, status, ports, and names of the running containers.

• It helps in monitoring and managing the containers on a Docker host.

• The command can be used with various options to filter and format the output as per requirements.

• Example: 'docker ps -a' lists all containers,...read more

docker system prune is used to clean up unused Docker resources.

• docker system prune helps to free up disk space by removing unused containers, images, networks, and volumes

• It can be used to remove stopped containers, dangling images, unused networks, and unused volumes

• The command can be customized with flags to specify which resources to prune

• Example: docker system prune -a removes all unused resources, including stopp

Ruby's return keyword is different from Java in terms of behavior and syntax.

• In Ruby, the return keyword is optional and can be omitted.

• Ruby's return keyword can be used to explicitly return a value from a method.

• In Java, the return keyword is mandatory and must be used to return a value from a method.

• Java's return keyword cannot be used to return from a block or lambda expression.

Variables in Ruby are declared by assigning a value to a name using the assignment operator (=).

• To declare a variable, simply write the name of the variable followed by the assignment operator (=) and the value.

• Ruby is dynamically typed, so you don't need to specify the type of the variable.

• Variables can hold any type of data, including numbers, strings, arrays, hashes, etc.

• Variable names in Ruby are case-sensitive and...read more

1. Devise - authentication solution. 2. Paperclip - file attachment management. 3. Cancancan - authorization solution. 4. Sidekiq - background job processing. 5. RSpec - testing framework.

• Devise: A flexible authentication solution for Rails applications.

• Paperclip: A file attachment management library for ActiveRecord.

• Cancancan: An authorization solution that provides a simple way to define abilities.

• Sidekiq: A backgrou...read more

Migrations in Rails are a way to manage database schema changes.

• Migrations are Ruby classes that help modify the database schema.

• They allow you to create, modify, or delete database tables, columns, and indexes.

• Migrations provide a version control system for the database schema.

• They ensure that all developers working on the project have the same database structure.

• Migrations can be easily rolled back if needed, making ...read more