Quick Revision

GK One-Line Question & Answer

15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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Computer Fundamentals → Introduction to Computer 38

Unix philosophy states?
Write programs that do one thing well and work together via text streams
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Which Linux distribution is most commonly used on servers?
Ubuntu Server / CentOS / Red Hat Enterprise Linux
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Kali Linux is used for?
Penetration testing and security auditing (preloaded security tools)
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Android is based on?
Linux kernel with custom runtime (ART)
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ChromeOS is based on?
Linux kernel with Chrome browser as main interface
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Which OS uses APK packages?
Android
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iOS App Store review process is?
Mandatory App Store review by Apple before app publication
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Package manager 'pip' is for?
Python packages
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npm is package manager for?
Node.js / JavaScript
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Virtual environment in Python (venv) is used to?
Create isolated Python environments with separate dependencies per project
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conda is a package manager for?
Python and R scientific computing packages and environments
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shebang line (#!/usr/bin/python3) in scripts?
Specifies which interpreter to use when script is executed directly
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Which SQL statement is used to create a new database?
CREATE DATABASE
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Which SQL command selects all columns?
SELECT *
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SQL ORDER BY default sort order is?
Ascending
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Which SQL keyword filters duplicate rows?
DISTINCT
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SQL LIKE operator uses which wildcard for multiple characters?
%
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SQL BETWEEN operator is?
Inclusive of both boundary values
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NULL in SQL represents?
Unknown or missing value
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IS NULL vs = NULL in SQL?
IS NULL is correct; = NULL always returns false (no value equals NULL)
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TRUNCATE vs DELETE in SQL?
TRUNCATE faster (removes all rows, can't rollback in many DBs); DELETE is slower but rollbackable
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DROP TABLE vs TRUNCATE TABLE?
DROP removes table structure AND data; TRUNCATE removes only data
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Which SQL clause groups rows with same values?
GROUP BY
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HAVING clause in SQL filters?
Groups created by GROUP BY after aggregation
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Which aggregate function calculates average?
AVG()
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SQL subquery is?
A nested SQL query inside another query
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Correlated subquery refers to?
A subquery that references a column from the outer query
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EXISTS operator in SQL?
Returns TRUE if subquery returns any rows
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UNION vs UNION ALL in SQL?
UNION removes duplicates; UNION ALL keeps all rows including duplicates
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EXCEPT (or MINUS in Oracle) returns?
Rows in first query not present in second query
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INTERSECT in SQL returns?
Rows common to both queries
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Which SQL function gets current date and time?
All of the above (varies by DBMS)
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CHAR vs VARCHAR in SQL?
CHAR is fixed-length; VARCHAR is variable-length (more efficient for varying text)
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Which SQL data type stores large text?
TEXT / CLOB (Character Large Object)
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BLOB in SQL stores?
Binary Large Objects — images, files, audio
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AUTO_INCREMENT in MySQL?
Automatically generates unique sequential integers for primary key
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Which MySQL command shows all databases?
SHOW DATABASES
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USE database_name in MySQL?
Selects/switches to specified database for subsequent queries
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Computer Fundamentals → Operating System Basics 1

iOS kernel is named?
XNU (X is Not Unix) — hybrid kernel from Mach and BSD
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Computer Fundamentals → Software and Hardware 1

Which command starts Python interpreter interactively?
python
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