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16
Computer_Architecture/CPU/The_Little_Man_computer.md
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@ -1,9 +1,9 @@
--- ---
categories: categories:
- Computer Architecture - Computer Architecture
tags: [CPU, processors] tags: [CPU]
--- ---
## The Little Man Computer ## The Little Man Computer
// TODO: Improve notes and learn how to use // TODO: Improve notes and learn how to use
@ -16,19 +16,19 @@ On the left is the instruction set. Each number constitutes and execution routin
Each row of the RAM has a denary address, 1 through to 99. Each address can hold three digits. Each row of the RAM has a denary address, 1 through to 99. Each address can hold three digits.
* So the instruction `560` would mean *load the number at address 60.* - So the instruction `560` would mean _load the number at address 60._
* The instruction `340` would mean *store a datum at address 40* - The instruction `340` would mean _store a datum at address 40_
### Working through a basic computation ### Working through a basic computation
We are going to add two numbers together as a basic example. We are going to add two numbers together as a basic example.
1. First we need to place the two numbers in RAM we are going to use `5` and `3` 1. First we need to place the two numbers in RAM we are going to use `5` and `3`
* At address `60` we will put the number `5` and at address `61` we will put the number `3` - At address `60` we will put the number `5` and at address `61` we will put the number `3`
* We are going to start at address `0` in the top left of the RAM grid - We are going to start at address `0` in the top left of the RAM grid
1. The first instruction will be *load address 60* which in the assembly will be `560` . We put this in address `0`, our starting point. 1. The first instruction will be _load address 60_ which in the assembly will be `560` . We put this in address `0`, our starting point.
1. This first instruction is now stored in the accumulator. 1. This first instruction is now stored in the accumulator.
1. Now we want to *add this number (in the accumulator) to the number in address 61* 1. Now we want to _add this number (in the accumulator) to the number in address 61_
1. This second instruction is `161` . We write this in address `1` 1. This second instruction is `161` . We write this in address `1`
1. Finally we want to store the output of the calculation in the RAM, let's say at address `62` 1. Finally we want to store the output of the calculation in the RAM, let's say at address `62`
1. So we store the command `362` at address `2` 1. So we store the command `362` at address `2`

2
Computer_Architecture/Chipset_and_controllers.md
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@ -2,7 +2,7 @@
categories: categories:
- Computer Architecture - Computer Architecture
- Hardware - Hardware
tags: [motherboard, chipset] tags: [motherboard]
--- ---
# Chipset and controllers # Chipset and controllers

2
Computer_Architecture/Hardware_Description_Language.md
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@ -2,7 +2,7 @@
categories: categories:
- Computer Architecture - Computer Architecture
- Hardware - Hardware
tags: [HDL, nand-to-tetris] tags: [nand-to-tetris]
--- ---
# Hardware Description Language # Hardware Description Language

2
Computer_Architecture/Hardware_abstraction_and_modularity.md
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@ -2,7 +2,7 @@
categories: categories:
- Computer Architecture - Computer Architecture
- Hardware - Hardware
tags: [abstraction, modules, nand-to-tetris] tags: [nand-to-tetris]
--- ---
# Hardware abstraction and modularity # Hardware abstraction and modularity

2
Computer_Architecture/Hardware_simulation.md
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@ -2,7 +2,7 @@
categories: categories:
- Computer Architecture - Computer Architecture
- Hardware - Hardware
tags: [HDL, nand-to-tetris] tags: [nand-to-tetris]
--- ---
# Hardware simulation # Hardware simulation

3
Data_Structures/Recursion.md
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--- ---
categories: categories:
- DSA - DSA
tags: tags:
- algorithms - algorithms
- data-structures
- recursion - recursion
--- ---

2
Databases/ACID_principle.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Databases - Databases
tags: [relational-database] tags: [relational-databases]
--- ---
# ACID principle # ACID principle

2
Databases/MongoDB/Validating_Mongoose_schemas.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Databases - Databases
tags: [mongodb, node-js, mongoose] tags: [mongo-db, mongoose, node-js]
--- ---
# Validating Mongoose schemas # Validating Mongoose schemas

2
Databases/REST/HTTP_request_types.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Networks - Networks
tags: [http] tags: []
--- ---
## GET ## GET

2
Databases/REST/RESTful_APIs.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Databases - Databases
tags: [apis, REST] tags: [APIs, REST]
--- ---
# RESTful APIs # RESTful APIs

2
Databases/Relational_Databases/Relational_database_architecture.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Databases - Databases
tags: [relational-database] tags: [relational-databases]
--- ---
# Relational database architecture # Relational database architecture

2
Databases/SQL/Autoincrement_for_unique_key_in_SQL.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Autoincrement and `SERIAL` # Autoincrement and `SERIAL`

2
Databases/SQL/Create_an_SQL_table.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Create an SQL table # Create an SQL table

2
Databases/SQL/Data_types_in_MySQL.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Data types in MySQL # Data types in MySQL

2
Databases/SQL/Delete_records_in_an_SQL_table.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Deleting data in SQL # Deleting data in SQL

2
Databases/SQL/Foreign_keys_in_SQL.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Creating views with foreign keys # Creating views with foreign keys

2
Databases/SQL/Insert_data_into_SQL_table.md
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categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Insert data into table with SQL `INSERT` statement # Insert data into table with SQL `INSERT` statement

2
Databases/SQL/Regular_expressions_in_SQL.md
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categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database, regex] tags: [SQL, relational-databases, regex]
--- ---
# Regular expressions in SQL # Regular expressions in SQL

2
Databases/SQL/Retrieve_data_from_SQL_table.md
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categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Retrieve data from table with SQL `SELECT` statement # Retrieve data from table with SQL `SELECT` statement

2
Databases/SQL/Update_an_SQL_table.md
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categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Updating an SQL table # Updating an SQL table

2
Databases/SQL/Update_existing_data_in_SQL_table.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Update existing data with the SQL `UPDATE` command # Update existing data with the SQL `UPDATE` command

2
Databases/SQL/Useful_operators_in_SQL.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Useful operators in SQL # Useful operators in SQL

2
Databases/SQL/Wildcards_in_SQL.md
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@ -2,7 +2,7 @@
categories: categories:
- Databases - Databases
- Programming Languages - Programming Languages
tags: [SQL, relational-database] tags: [SQL, relational-databases]
--- ---
# Wildcards in SQL # Wildcards in SQL

2
Electronics_and_Hardware/Analogue_and_digital.md
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@ -2,7 +2,7 @@
title: Analogue and digital title: Analogue and digital
categories: categories:
- Hardware - Hardware
tags: [analogue, digital] tags: [analogue]
--- ---
# Analogue and digital # Analogue and digital

2
Electronics_and_Hardware/Analogue_circuits/Circuits.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Electronics - Electronics
tags: [electricity, electrical-circuits] tags: [electricity, circuits]
--- ---
# Circuits # Circuits

2
Electronics_and_Hardware/Analogue_circuits/LEDs.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Electronics - Electronics
tags: [electricity, electrical-circuits] tags: [electricity, circuits]
--- ---
# LEDs # LEDs

2
Electronics_and_Hardware/Binary/Binary_encoding_of_text.md
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@ -2,7 +2,7 @@
title: Text encoding title: Text encoding
categories: categories:
- Computer Architecture - Computer Architecture
tags: [binary, binary-encoding, ascii, unicode, utf-8] tags: [binary, binary-encoding]
--- ---
# Text encoding # Text encoding

2
Electronics_and_Hardware/Binary/Why_computers_use_binary.md
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@ -3,7 +3,7 @@ title: Why computers use binary
categories: categories:
- Mathematics - Mathematics
- Computer Architecture - Computer Architecture
tags: [binary, bits] tags: [binary]
--- ---
# Why computers use binary # Why computers use binary

2
Electronics_and_Hardware/Digital_circuits/Digital_circuits.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Electronics - Electronics
tags: [electrical-circuits] tags: [circuits]
--- ---
# Digital circuits # Digital circuits

2
Electronics_and_Hardware/Physics_of_electricity/Ohms_Law.md
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@ -2,7 +2,7 @@
title: Ohm's Law title: Ohm's Law
categories: categories:
- Electronics - Electronics
tags: [physics, electricity, electrical-resistance] tags: [physics, electricity]
--- ---
# Ohm's Law # Ohm's Law

2
Linux/Procedural/Compile_from_source.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Linux - Linux
tags: [compilers] tags: []
--- ---
# Compile package from source # Compile package from source

2
Linux/Procedural/Create_timed_systemd_job.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Linux - Linux
tags: [systems-programming, systemd] tags: [systems-programming]
--- ---
# Create timed `systemd` job # Create timed `systemd` job

2
Linux/Procedural/Pacman.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Linux - Linux
tags: [package-management] tags: []
--- ---
# Pacman # Pacman

7
Linux/Procedural/User_management.md
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@ -1,8 +1,9 @@
--- ---
categories: categories:
- Linux - Linux
tags: [user-management] tags: []
--- ---
# User management # User management
## Switch user ## Switch user
@ -11,6 +12,6 @@ If already logged in as a user you can switch users with the command `su - [user
## Login as root ## Login as root
If you are logged in as a standard user, if you use `su -` without specifying a username, then it will assume you wish to log in as root. If you are logged in as a standard user, if you use `su -` without specifying a username, then it will assume you wish to log in as root.
If you wish to login as root in the tty at startup, then use `root` as the username. If you wish to login as root in the tty at startup, then use `root` as the username.

2
Linux/journald.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Linux - Linux
tags: [journaling, systemd, systems-programming] tags: [systems-programming]
--- ---
# `journald` # `journald`

2
Linux/systemd.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Linux - Linux
tags: [systems-programming, systemd] tags: [systems-programming]
--- ---
# `systemd` # `systemd`

2
Logic/Laws_and_theorems.md/DeMorgan's_Laws.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [logic, laws] tags: []
--- ---
# DeMorgan's Laws # DeMorgan's Laws

2
Logic/Proofs/Biconditional_Elimination.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Biconditional Elimination # Biconditional Elimination

2
Logic/Proofs/Biconditional_Introduction.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Biconditional introduction # Biconditional introduction

2
Logic/Proofs/Conditional_Elimination.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Conditional elimination # Conditional elimination

2
Logic/Proofs/Conditional_Introduction.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Conditional Introduction # Conditional Introduction

2
Logic/Proofs/Conjunction_Elimination.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Conditional Elimination # Conditional Elimination

2
Logic/Proofs/Conjunction_Introduction.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
If two conjuncts have each been independently derived then they can be conjoined. Also known more simply as _Conjunction_ If two conjuncts have each been independently derived then they can be conjoined. Also known more simply as _Conjunction_

2
Logic/Proofs/Disjunction_Elimination.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Disjunction Elimination # Disjunction Elimination

2
Logic/Proofs/Disjunction_Introduction.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Disjunction Introduction # Disjunction Introduction

2
Logic/Proofs/Negation_Elimination.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Negation Elimination # Negation Elimination

2
Logic/Proofs/Negation_Introduction.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Negation Introduction # Negation Introduction

2
Logic/Proofs/Reiteration.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Logic - Logic
tags: [derivation-rules] tags: []
--- ---
# Reiteration # Reiteration

2
Logic/Propositional_logic/Boolean_function_synthesis.md
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@ -2,7 +2,7 @@
categories: categories:
- Logic - Logic
- Computer Architecture - Computer Architecture
tags: [logic, propositional-logic, nand-to-tetris] tags: [propositional-logic, nand-to-tetris]
--- ---
# Boolean function synthesis # Boolean function synthesis

2
Logic/Propositional_logic/Boolean_functions.md
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@ -2,7 +2,7 @@
categories: categories:
- Logic - Logic
- Computer Architecture - Computer Architecture
tags: [logic, propositional-logic, nand-to-tetris] tags: [propositional-logic, nand-to-tetris]
--- ---
# Boolean functions # Boolean functions

3
Logic/Propositional_logic/Truth-tables.md
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@ -1,7 +1,8 @@
--- ---
categories: categories:
- Mathematics - Mathematics
tags: [logic] - Logic
tags: []
--- ---
# Truth-tables # Truth-tables

2
Logic/Propositional_logic/Truth-trees.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Mathematics - Mathematics
tags: [logic] tags: []
--- ---
## Rationale ## Rationale

1
Mathematics/Prealgebra/Add_Subtract_Fractions.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- division
--- ---
# Adding and subtracting fractions # Adding and subtracting fractions

1
Mathematics/Prealgebra/Dividing_fractions.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- division
--- ---
# Dividing fractions # Dividing fractions

2
Mathematics/Prealgebra/Factors_and_divisors.md
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@ -3,8 +3,6 @@ categories:
- Mathematics - Mathematics
tags: tags:
- prealgebra - prealgebra
- factors
- divisors
--- ---
## Factors and divisors ## Factors and divisors

1
Mathematics/Prealgebra/Increasing_fractions_to_their_highest_terms.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- divisors
--- ---
Given the equivalence between factors and divisors we can increase fractions to higher terms in a very similar way to when we reduce fractions. In the latter case we are dividing by divisors to reduce. In the former, we are multiplying by factors to increase. Given the equivalence between factors and divisors we can increase fractions to higher terms in a very similar way to when we reduce fractions. In the latter case we are dividing by divisors to reduce. In the former, we are multiplying by factors to increase.

1
Mathematics/Prealgebra/Inversion_of_operators.md
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@ -3,7 +3,6 @@ categories:
- Mathematics - Mathematics
tags: tags:
- prealgebra - prealgebra
- operators
--- ---
## Addition, subtraction ## Addition, subtraction

2
Mathematics/Prealgebra/Multiplying_fractions.md
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@ -4,7 +4,7 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- multiplication - arithmetic
--- ---
# Multiplying fractions # Multiplying fractions

3
Mathematics/Prealgebra/Prime_factorization.md
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@ -3,8 +3,7 @@ categories:
- Mathematics - Mathematics
tags: tags:
- prealgebra - prealgebra
- factors - number-theory
- primes
--- ---
### Prime factorisation ### Prime factorisation

2
Mathematics/Prealgebra/Primes_and_composites.md
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@ -3,7 +3,7 @@ categories:
- Mathematics - Mathematics
tags: tags:
- prealgebra - prealgebra
- primes - number-theory
--- ---
## Prime and composite numbers ## Prime and composite numbers

1
Mathematics/Prealgebra/Reciprocals.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- division
- theorems - theorems
--- ---

1
Mathematics/Prealgebra/Reducing_fractions.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- prealgebra - prealgebra
- fractions - fractions
- divisors
--- ---
## Reducing fractions to their lowest terms ## Reducing fractions to their lowest terms

1
Operating_Systems/Boot_process.md
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@ -4,7 +4,6 @@ categories:
- Operating Systems - Operating Systems
tags: tags:
- disks - disks
- bootloader
--- ---
# The boot process # The boot process

1
Operating_Systems/Disks/Filesystems.md
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@ -4,7 +4,6 @@ categories:
- Operating Systems - Operating Systems
tags: tags:
- disks - disks
- filesystems
--- ---
# Filesystems # Filesystems

1
Operating_Systems/Disks/Partitions.md
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@ -5,7 +5,6 @@ categories:
tags: tags:
- disks - disks
- devices
--- ---
# Disk partitions # Disk partitions

1
Operating_Systems/Disks/Swap_space.md
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@ -5,7 +5,6 @@ categories:
tags: tags:
- memory - memory
- disks - disks
- devices
--- ---
# Swap space # Swap space

1
Operating_Systems/Disks/What_are_disks.md
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@ -4,7 +4,6 @@ categories:
- Operating Systems - Operating Systems
tags: tags:
- disks - disks
- devices
--- ---
# What are disks? # What are disks?

2
Operating_Systems/The_Kernel.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Operating Systems - Operating Systems
tags: [systems-programming, processes, memory] tags: [systems-programming, memory]
--- ---
# The Kernel # The Kernel

5
Programming_Languages/Frameworks/React/Hooks/Memoization.md
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@ -5,7 +5,6 @@ tags:
- javascript - javascript
- react - react
- react-hooks - react-hooks
- memoization
--- ---
# Memoization with `useCallback` and `useMemo` # Memoization with `useCallback` and `useMemo`
@ -49,7 +48,7 @@ const handleSubmit = useCallback(
.finally(() => setPendSaveConfig(false)) .finally(() => setPendSaveConfig(false))
.catch((err) => console.error(err)); .catch((err) => console.error(err));
}, },
[blockId, project_id], [blockId, project_id]
); );
``` ```
@ -103,6 +102,6 @@ const List = React.useMemo(
itemProp1: expensiveFunction(props.first), itemProp1: expensiveFunction(props.first),
itemProp2: anotherPriceyFunction(props.second), itemProp2: anotherPriceyFunction(props.second),
})), })),
[listOfItems], [listOfItems]
); );
``` ```

1
Programming_Languages/Node/Architecture/Event_loop.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- async
--- ---
# The Event Loop # The Event Loop

1
Programming_Languages/Node/Architecture/Module_wrapping_at_runtime.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
## The Module Wrapper Function ## The Module Wrapper Function

1
Programming_Languages/Node/Architecture/Ports.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
# Ports # Ports

1
Programming_Languages/Node/Modules/Core/Node_JS_events_module.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
# Node.js `events` module # Node.js `events` module

1
Programming_Languages/Node/Modules/Core/fs.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
# `fs` module # `fs` module

1
Programming_Languages/Node/Modules/Core/http.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
# `http` module # `http` module

9
Programming_Languages/Node/Modules/Modules.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- node-modules
--- ---
# Modules # Modules
@ -65,7 +64,7 @@ module.exports = function (...params) {
Note the module is unnamed. We would name it when we import: Note the module is unnamed. We would name it when we import:
```js ```js
const myFunction = require('./filenme'); const myFunction = require("./filenme");
``` ```
### Exporting sub-components from a module ### Exporting sub-components from a module
@ -85,7 +84,7 @@ var nonExportedVar = true;
This time the exports are already name so we would import with the following: This time the exports are already name so we would import with the following:
```js ```js
const {myFunc, aVar} = require('./filename'); const { myFunc, aVar } = require("./filename");
``` ```
We can also do the exporting at the bottom when the individual components are named: We can also do the exporting at the bottom when the individual components are named:
@ -104,13 +103,13 @@ exports.myNamedFunc = myNamedFunc;
exports.differentName = anotherNamedFunc; // We can use different names exports.differentName = anotherNamedFunc; // We can use different names
// Or we could export them together // Or we could export them together
module.exports = {myNamedFunc, anotherNamedFunc}; module.exports = { myNamedFunc, anotherNamedFunc };
``` ```
The import is the same: The import is the same:
```js ```js
const {myNamedFunc, anotherNamedFunc} = require('./modules/multiExports'); const { myNamedFunc, anotherNamedFunc } = require("./modules/multiExports");
``` ```
## Structuring modules ## Structuring modules

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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- npm
--- ---
# Package management # Package management

2
Programming_Languages/Node/REST_APIs/Validation.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Programming Languages - Programming Languages
tags: [backend, node-js, REST, APIs, validation] tags: [backend, node-js, REST, APIs]
--- ---
# Creating a RESTful API: Validation # Creating a RESTful API: Validation

1
Programming_Languages/Node/Streams.md
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@ -4,7 +4,6 @@ categories:
tags: tags:
- backend - backend
- node-js - node-js
- streams
--- ---
# Handling streams with `fs` # Handling streams with `fs`

2
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@ -5,7 +5,7 @@ tags:
- shell - shell
--- ---
# Quote marks # Quote marks in Bash
## Single-quotes (aka _strong_ quotes) ## Single-quotes (aka _strong_ quotes)

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@ -22,7 +22,11 @@ awk [program] file1, file2, file3
awk -f [ref_to_script_file] file1, file2, file3 awk -f [ref_to_script_file] file1, file2, file3
``` ```
We can also obviously pipe to it. We can also pipe to it. This piped command receives output from the `echo` command and prints the value in the last field for each record:
```bash
echo -e "1 2 3 5\n2 2 3 8" | awk '{print $(NF)}'
```
## Syntactic structure ## Syntactic structure
@ -54,6 +58,8 @@ Alfred 65
Kate 46 Kate 46
``` ```
> `awk` particularly lends itself to inputs that are structured by whitespace or in columns, like what you get from commands like `ls` and `grep`
### Patterns and actions ### Patterns and actions
The basic structure of an `awk` script is as follows: The basic structure of an `awk` script is as follows:
@ -146,4 +152,38 @@ awk '$2 >= 90 { print $0 }' scores.txt
This returns the records where there is a secondary numerical field that is greater than 90. This returns the records where there is a secondary numerical field that is greater than 90.
**_Match a field against a regular expression_**
```bash
awk '$1 ~ /^[b,c]/ {print $1}' words.txt
```
This matches all the fields in the `$1` place that begin with 'b' or 'c'.
The tilde is the regex match operator. You must be passing a regex to use it, otherwise use `==`.
## Syntactic shorthands
- For a statement like `awk 'length($1) > 5 { print $0 }' list.txt`. We actually don't need to include the `{ print $0 }` action, as this is the default behaviour and it is implied. We could have just put `length($1) > 5 list.txt`.
https://zetcode.com/lang/awk/ https://zetcode.com/lang/awk/
## Built-in variables
### `NF`
The value of `NF` is the **number** of **fields** in the current record. `Awk` automatically updates the value of `NF` every time it reads a record.
No matter how many fields there are, the last value in a record can always be represented by `$NF`.
### `NR`
`NR` represents the **number** of **records**. It is set at the point at which the file is read.
### `FS`
`FS` represents the **field separator**. The default field separator is a space. We can specify a different separator with the `-F` flag. E.g to separate by comma:
```bash
awk -F, '{print $1 }' list.txt
```

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@ -3,7 +3,6 @@ categories:
- Programming Languages - Programming Languages
tags: tags:
- shell - shell
- unix
--- ---
## Unix based systems ## Unix based systems

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@ -3,7 +3,6 @@ categories:
- Programming Languages - Programming Languages
tags: tags:
- shell - shell
- processes
--- ---
# Processes (`ps`) # Processes (`ps`)

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@ -5,7 +5,7 @@ tags:
- shell - shell
--- ---
# Test in bash # Test values in Bash
`test` is a built-in command that is used to compare values or determine whether something is the case. `test` is a built-in command that is used to compare values or determine whether something is the case.

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@ -2,7 +2,6 @@
categories: categories:
- Mathematics - Mathematics
tags: tags:
- logic
- set-theory - set-theory
- theorems - theorems
--- ---

2
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@ -1,8 +1,8 @@
--- ---
categories: categories:
- Mathematics - Mathematics
- Logic
tags: tags:
- logic
- set-theory - set-theory
--- ---

3
Software_Engineering/Call_stack.md
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@ -1,8 +1,7 @@
--- ---
categories: categories:
- Software Engineering - Software Engineering
tags: tags: []
- callstack
--- ---
# The call-stack # The call-stack

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Software_Engineering/Semantic_versioning.md
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@ -1,7 +1,7 @@
--- ---
categories: categories:
- Software Engineering - Software Engineering
tags: [semver] tags: []
--- ---
# Semantic versioning # Semantic versioning

3
Software_Engineering/The_Pragmatic_Programmer_1999.md
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@ -1,8 +1,7 @@
--- ---
categories: categories:
- Software Engineering - Software Engineering
tags: tags: []
- resources
--- ---
## General ## General

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Theory_of_Computation/Defining_a_computer.md
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@ -3,9 +3,10 @@ categories:
- Computer Architecture - Computer Architecture
tags: tags:
- theory-of-computation - theory-of-computation
- history
--- ---
# Defining a computer
> A general-purpose computer is one that, given the appropriate instructions and required time, should be able to perform most common computing tasks. > A general-purpose computer is one that, given the appropriate instructions and required time, should be able to perform most common computing tasks.
This sets a general purpose computer aside from a special-purpose computer, like the one you might find in your dishwasher which may have its instructions hardwired or coded into the machine. Special purpose computers only perform a single set of tasks according to prewritten instructions. We’ll take the term _computer_ to mean general purpose computer. This sets a general purpose computer aside from a special-purpose computer, like the one you might find in your dishwasher which may have its instructions hardwired or coded into the machine. Special purpose computers only perform a single set of tasks according to prewritten instructions. We’ll take the term _computer_ to mean general purpose computer.

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@ -3,7 +3,6 @@ categories:
- Computer Architecture - Computer Architecture
tags: tags:
- theory-of-computation - theory-of-computation
- turing
--- ---
## What is a Turing Machine? ## What is a Turing Machine?