10 Super Powerful Linux Commands

We always say that the most powerful Linux tools are its Command lines. This is because you can do about everything right from your command line. You can easily explain your computer exactly what you require and it comes back to you with appropriate results. Infact there are some commands that make this tool even more powerful! Here we bring to you a list of 10 such commands that work like energy drinks for you Linux machines!

Solving "perl: warning: Setting locale failed" in Ubuntu

It is happen because locale setting needs to be reconfigured. To do that, just type this in terminal

sudo dpkg-reconfigure locales

If it doesn't successfull, try to set locale first

sudo locale-gen en_US en_US.UTF-8

and then type dpkg again.

source

Install Squid Proxy Ubuntu Server

• Install Squid

sudo apt-get install squid

• Set squid to run after startup

update-rc.d squid3 defaults

• Open squid configuration file

sudo nano /etc/squid/squid.config

• Add this to the first line of squid.conf to use ipv4 only

dns_v4_first on

• Press Ctrl+w to search "http_access deny all"

• clear "#"

• Search "acl localnet" with Ctrl+w

• add line "acl localnet src your-ip-public"

• Press Ctrl+w to search "http_access allow"

• add line "http_access allow localnet"

• Press Ctrl+o and then press enter to save edited file

• restart squid service

sudo service squid3 restart

NB:

• You can change localnet to whatever you want
• To change proxy port, search "http_port 3128" and change 3128 with port you want

Source

How Priority Queue in Java is Working

Source Code

1. import java.util.*;  
2. class PQ{  
3.     static class PQsort implements Comparator<Integer>{   // inverse sort  
4.         public int compare(Integer one, Integer two){  
5.             return two - one;           // unboxing  
6.         }  
7.     }  
8.     public static void main(String[] args){  
9.         int[] ia = {1,5,3,7,6,9,8};         // unordered data  
10.         PriorityQueue<Integer> pq1 =   
11.             new PriorityQueue<Integer>();     // use natural order  
12.           
13.         for (int x : ia)                // load queue  
14.             pq1.offer(x);  
15.               
16.         for (int x : ia)                // review queue  
17.             System.out.print(pq1.poll() + " ");  
18.         System.out.println("");  
19.               
20.         PQsort pqs = new PQsort();          // get a Comparator  
21.         PriorityQueue<Integer> pq2 =   
22.             new PriorityQueue<Integer>(10,pqs);   // use Comparator  
23.               
24.         for (int x : ia)                // load queue  
25.             pq2.offer(x);  
26.           
27.           
28.         for (int x : ia)                // review queue  
29.             System.out.print(pq2.poll() + " ");  
30.           
31.         System.out.println(" ");  
32.     }  
33. } 

Backup and Restore Database MySQL

For backup all databases

  mysqldump -u username -ppassword --all-databases > /tmp/alldatabases.sql

For backup spesific database

 mysqldump -u username -ppassword --databases databasename > /tmp/filename.sql

For restore

mysql -u username -ppassword databasename < /tmp/filename.sql

Instaling Kubuntu Desktop without KDE Application

Just type this in terminal

sudo apt-get install --no-install-recommends kubuntu-desktop

Setting Proxy for apt-get in Ubuntu

1. Open terminal
2. Type this
   

   sudo nano /etc/apt/apt.conf

3. Add this line if there in no authentication in your proxy
   

   Acquire::http::proxy "http://proxyserver:port/";

4. Add this if there is authentication in your proxy
   

   Acquire::http::proxy "http://username:password@proxyserver:port/";

5. Press Ctrl+x and then press y