Notes, abstracts, papers, exams and problems of Computers

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Essential Linux Commands & File System Structure

Classified in Computers

Written at on English with a size of 7.16 KB.

Linux File System Structure: An archive of Linux is associated with 3 parts: superblock, inode table, and data blocks.

Network Ports: To see the ports assigned to services.

Display Active TCP/IP Connections: netstat -a

User Management:

  • Create password: passwd (user)
  • Add user to group: usermod -g group_name
  • Disable: 60001
  • Enable: 60002

Practical Commands:

Add User: adduser

  1. Change folder privileges: chmod
  2. Check privileges: ls -de (see if you changed privileges)
  1. Create a user: useradd newuser
    passwd newuser
  2. Create a directory: The command mkdir is used to create directories:
    mkdir mydirectory
  3. Create a report: ps -aux >> reporte.txt
  4. Directories associated with the user: -d dirname
  5. Changing permission: chmod 744 file.txt /file.txt
  6. Change owner: chown
    Entering
... Continue reading "Essential Linux Commands & File System Structure" »
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Shell script

Classified in Computers

Written at on English with a size of 2.47 KB.

Ejercicio de descuentos:

#!/bin/bash

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

until [ $idavuelta=="s" ] || [ $idavuelta=="n" ]; do

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

done

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

until [ $carnetjoven="s" ] || [ $carnetjoven="n" ]; do

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

done

descuento=0 billete=20

if [ $idavuelta="s" ]; then

descuento=20

billete=" expr $billete \* 2'

fi

if [ $carnetjoven="s" ]j then

descuento=30

fi

costefinal=`expr $billete \* \( 100 - $descuento \) / 100`

echo "El precio final del billete es $costefinal"



Ejercicio de medias:

#!/bin/bash

acu=0

cont=0

read -p "Introduce un numero: " num

while [ $num -ne 0 ]; do

acu=`expr $acu + $num`

cont=... Continue reading "Shell script" »

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C++ Code Examples: Essential Algorithms & Programs

Classified in Computers

Written at on English with a size of 5.54 KB.

C++ Code Examples: Essential Algorithms & Programs

Here are some fundamental C++ code examples covering various algorithms and programming concepts:

Factorial Calculation

#include <iostream>
using namespace std;

long factorial(int x) {
 int i, f = 1;
 for (i = 1; i <= x; i++) {
 f = f * i;
 }
 return f;
}

int main() {
 int n;
 cout << "Enter the number: ";
 cin >> n;
 if (n < 0) {
 cout << "Factorial is not defined for negative numbers";
 } else {
 cout << "Factorial = " << factorial(n);
 }
 return 0;
}

String Length Finder

#include <iostream>
using namespace std;

int main() {
 int length = 0, i;
 char s[20];
 cout << "Enter the string: ";
 cin.getline(s, 20);
 for (i = 0; s[i] != '\0'
... Continue reading "C++ Code Examples: Essential Algorithms & Programs" »
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dsdfs

Classified in Computers

Written at on English with a size of 7.22 KB.

Kako si lep danes 

What is Lorem Ipsum?

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

What is Lorem Ipsum?

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard... Continue reading "dsdfs" »

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Programming Concepts: Constants, Constructs, and Operators

Classified in Computers

Written at on English with a size of 1.72 KB.

Programming Fundamentals

What is a Constant?

A constant is a data value that remains unchanged during the execution of a program.

Three Programming Constructs

The three fundamental programming constructs are: selection, iteration, and sequence.

Logical Operators

One example of a logical operator is AND.

  • Operator: and
  • Description: Logical AND: True if both operands are true.
  • Syntax: x and y

Functions vs. Procedures

Difference: A function is typically used to calculate a value from a given input, while a procedure is a set of commands executed in a specific order.

Similarity: Functions must return a value, but in stored procedures, it is optional. Procedures can return zero or multiple values. Functions usually have only input parameters, whereas procedures... Continue reading "Programming Concepts: Constants, Constructs, and Operators" »

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Java Arithmetic Operations Web App

Classified in Computers

Written at on English with a size of 1.24 KB.

Arithmetic Operations in Java

Input Form

Enter number 1:
Enter number 2:
  • Addition
  • Subtraction
  • Multiplication
  • Division

<% String num1Str = request.getParameter("num1"); String num2Str = request.getParameter("num2"); String operation = request.getParameter("operation"); if (num1Str != null && num2Str != null && !num1Str.isEmpty() && !num2Str.isEmpty() && operation != null) { double num1 = Double.parseDouble(num1Str); double num2 = Double.parseDouble(num2Str); double result = 0; switch (operation) { case "add": result = num1 + num2; out.println("

Result: " + result + "

"); break; case "subtract": result = num1 - num2; out.println("

Result: " + result + "

"); break; case "multiply": result = num1 * num2; out.println("... Continue reading "Java Arithmetic Operations Web App" »

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Refer to the exhibit. When a static IP address is being configured on the host, what address should be used for the default gateway

Classified in Computers

Written at on English with a size of 4.69 KB.

HOSTàROUTER: 1

ENABLE

CONFIGURE TERMINAL

INTERFACE GIGABITETHERNET 0/0

IP ADDRESS 192.168.1.126 255.255.255.224

NO SHUTDOWN

EXIT

INTERFACE GIGABITEETHERNET 0/1

IP ADDRESS 192.168.1.158 255.255.255.240

NO SHUTDOWN

HOSTàSWITCH 2

ENABLE

CONFIFURE TERMINAL

INTERFACE VLAN 1

IP ADDRESS 192.168.1.157 255.255.255.240

NO SHUTDOWN

HOST/ROUTER 3

EXIT (LLEGAR AL CONFIGURE TERMINAL)

HOSTNAME MIDDLE

ENABLE SECRET CISCO

LINE CONSOLE 0

PASSWORD CLASS

LOGIN

EXIT

SECURITY PASSWORD MIN-LENGTH 10

SERVICE PASSWORD ENCRYPTION

IP DOMAIN-NAME CISCO

CRYPTON KEY GENERATE RSA

1024

EXIT

USERNAME CICLOS

LINE VTY 0 4

LOGIN LOCAL

TRANSPORT INPUT SSH

EXIT

INTERFACE GIBABITEETHERNET 0/0

IPV6 ADDRESS 2001:DB8:ACAD:A::1/64

IPV6 ADDRESS FE80::1 LIN

EXIT

GIBABITETHERNET 0/1

IPV6 ADDRESS 2001:DB8:ACAD:B::1/64

IPV6

... Continue reading "Refer to the exhibit. When a static IP address is being configured on the host, what address should be used for the default gateway" »
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Understanding Computer Viruses and Network Topologies

Classified in Computers

Written at on English with a size of 5.9 KB.

A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code.[1] When this replication succeeds, the affected areas are then said to be 'infected' with a computer virus.[2][3]

Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to initially infect systems and to spread the virus. The vast majority of viruses target systems running Microsoft Windows,[4][5][6] employing a variety of mechanisms to infect new hosts,[7] and often using complex anti-detection/stealth strategies to evade antivirus software.[8][9][10][11] Motives for creating viruses can include seeking profit (e.g., with ransomware), desire... Continue reading "Understanding Computer Viruses and Network Topologies" »

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Content

Classified in Computers

Written at on English with a size of 9.51 KB.

Javascript Continued

  1. The document.GetElementById() method returns the DOM node whose id attribute is the same as the method's parameter.
    Ex: document.GetElementById("early_languages") returns the p node in the HTML below.

  2. The document.GetElementsByTagName() method returns an array containing all the DOM nodes whose type is the same as the method's parameter.
    Ex: document.GetElementsByTagName("li") returns a list of the four li nodes from in the HTML below.

  3. The document.GetElementsByClassName() method returns an array containing all the DOM nodes whose class attribute matches the method's parameter.
    Ex: document.GetElementsByClassName("traditional") returns an array containing the ol node with the class attribute matching the word traditional.

... Continue reading "Content" »
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Using Proximity, White Space, Alignment, Contrast, and Repetition in Design

Classified in Computers

Written at on English with a size of 1.05 KB.

Proximity

Proximity is all about using visual spaces to show relationships in your content. We can group the items in blocks of text or elements in the graphic to take visual emphasis.

White Space

White space, also known as negative space, refers to the spaces between your content, between lines, and even the margins. White space defines and separates different sections.

Alignment

We can separate text boxes, images, etc. by imagining their content as a range inside of a grid. Centering the images to the text and using equal size margins can create a visually pleasing alignment.

Contrast

Contrast means that one item is different from another. We can create contrast using color, size, shape, or contrasting styles of text. Hierarchy, a visual technique... Continue reading "Using Proximity, White Space, Alignment, Contrast, and Repetition in Design" »

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