LINUX

FILE AND DIRECTORY COMMANDS
# List all files in a long listing (detailed) format
ls -al

# List all files by name only
ls

# Display the present working directory
pwd

# Create a directory
mkdir directory_name

# Remove (delete) file
rm file

# Remove the directory and its contents recursively
rm -r directory_name

# Force removal of file
rm -f file_name

# Forcefully remove directory recursively
rm -rf directory_name

# Copy file1 to file2
cp file1 file2

# Copy source_directory recursively to destination. If destination exists, copy source_directory into destination,
otherwise create destination with the contents of source_directory.
cp -r source_directory destination

# Rename or move file1 to file2. If file2 is an existing directory, move file1 into directory file2
mv file1 file2

# Create symbolic link to linkname
ln -s /path/to/file linkname

# Create an empty file.
touch file

# View the contents of file
cat file

#can run last command with sudo using
sudo !!
# can exit root from
 su <user_name> ==> su supuni

# Display the last 10 lines of file and "follow" the file as it grows.
tail -f file
example----
tail -f prod.log ==> can view all logs
tail -1000 prod.log ==> show last 1000 lines
tail -1000 prod.log | grep CRITICAL (show only critical errors)

#Remove process from always start when computer on
#show all the upladed processes
ls /etc/init.d/

#remove it by
sudo update-rc.d -f <process_name>.remove

# start services and stop
service <process_name> stop
service <process_name> start
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PROCESS MANAGEMENT
# Display your currently running processes
ps

# Display all the currently running processes on the system.
ps aux

# Display process information for processname
ps aux | grep processname

# Display cpu usage memory usage
top

# Kill process with process ID of pid
kill pid


INSTALL PROGRAMS TO UBUNTU SYSTEM

#Update latest  versions
	npm install npm@latest -g

#install vim
yum install vim

#adb install
sudo apt-get install adb

#install react-native
sudo apt-get install react-native

#How to repair ubuntu selection

1. verify that secure-boot disabled
2.Insert Ubuntu CD and try with Ubuntu cd
3.open terminal
4.sudo apt-add-repository ppa:yannubuntu/boot-repair
5.sudo apt-get update
6.sudo apt-get install -y boot-repair
7.boot-repair

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 SSH LOGINS

# Connect to host as user
ssh user@host

# Normal Method
ssh -i <path to file> user@host_name
ssh -i .ssh/id_rsa.pub ubuntu@siplo.lk
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FILE TRANSFERS
# Secure copy file.txt to the /tmp folder on server
scp file.txt server:/tmp

# Copy *.html files from server to the local /tmp folder.
scp server:/var/www/* .html /tmp
	scp root@192.168.8.125:/usr/share/freeswitch/conf/vanilla/vars.xml  /home/pi/
local machine to server
	scp /home/supuni/ubuntu/jitsi-images/  meetrix:/home/ubuntu

# Copy all files and directories recursively from server to the current system's /tmp folder.
scp -r server:/var/www /tmp
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DIRECTORY NAVIGATION
# To go up one level of the directory tree.
cd ..

# Go to the $HOME directory
cd

# Change to the /etc directory
cd /etc
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SYSTEM INFORMATION

# Show the current date and time
date

# Show this month's calendar
cal

# Display USB devices
lsusb -tv
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 FILE PERMISSIONS


         PERMISSION      EXAMPLE

         U   G   W
        rwx rwx rwx     chmod 777 filename
        rwx rwx r-x     chmod 775 filename
        rwx r-x r-x     chmod 755 filename
        rw- rw- r--     chmod 664 filename
        rw- r-- r--     chmod 644 filename

# NOTE: Use 777 sparingly!

        LEGEND
        U = User
        G = Group
        W = World

        r = Read
        w = write
        x = execute
        - = no access
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NETWORKING

# Display all network interfaces and ip address
ifconfig -a

# Send ICMP echo request to host
ping ip_address

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ARCHIEVES

#Compress an Entire Directory or a Single File
tar -czvf name-of-archive.tar.gz /path/to/directory-or-file
	tar -cvf /tmp/freeswitch_conf.tar /etc/freeswitch

- c: Create an archive.
-z: Compress the archive with gzip.
-v: Display progress in the terminal while creating the archive, also known as “verbose” mode. The v is always optional in these commands, but it’s helpful.
-f: Allows you to specify the filename of the archive.

#Extract an Archive
tar -xzvf archive.tar.gz -C /tmp
	tar -xvf /tmp/freeswitch_conf.tar /etc/freeswitch
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SEARCH

# Search for pattern in file
grep pattern file

# Search recursively for pattern in directory
grep -r pattern directory

# Find files and directories by name
locate name

# Find files in /home/john that start with "prefix".
find /home/john -name 'prefix*'

# Find files larger than 100MB in /home
find /home -size +100M
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DISK USAGE

# Show free and used space on mounted filesystems
df -h

# Display disks partitions sizes and types
fdisk -l

#can view image sizes
identify <jpg_name>.jpg

ImageMagick is a suite of command-line utilities for resizing, converting

convert howtogeek.png howtogeek.jpg //converting between format
convert howtogeek.png -quality 95 howtogeek.jpg //specify compression level
convert example.png -resize 200x100 example.png //resize image
convert example.png -resize 200x100! example.png // not considering ratio
convert example.png -resize 200 example.png // consider only width
convert example.png -resize x100 example.png // consider only height
convert howtogeek.jpg -rotate 90 howtogeek-rotated.jpg // rotate image

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MYSQL
1. Log into mysql:
	mysql -u [username] -p;(will prompt for password)

  data types (INTEGER,FLOAT, DECIMAL(i, j), CHAR(n), VARCHAR(n))
  DATE:
  • Made up of year-month-day in the format yyyy-mm-dd
  TIME:
  • Made up of hour:minute:second in the format hh:mm:ss
  TIME(i):
  • Made up of hour:minute:second plus i additional digits specifying fractions of a second
  • format is hh:mm:ss:ii...i
  TIMESTAMP:
  • Has both DATE and TIME components

2. Show all databases:
	SHOW DATABASES;

3. Access database:
	mysql -u [username] -p [database](will prompt for password)

4. Create new database:
	CREATE DATABASE [database_name];
      An error occurs if database exists, Check if the database is existing
      DROP DATABASE IF EXISTS [database_name];
      CREATE DATABASE [database_name];

      CREATE DATABASE IF NOT EXISTS Department;

5. Select database:
	USE [database_name];

6. Determine what database is in use:
	 SELECT DATABASE();

7. Show all tables:
	 SHOW TABLES;

8. Show table structure:
	 DESCRIBE [table_name];

9. List all indexes on a table:
	show index from [table];

10. Create new table with columns:
    CREATE TABLE DEPARTMENT
  ( DNAME VARCHAR(10) NOT NULL,
    DNUMBER INTEGER NOT NULL,
    MGRSSN CHAR(9),
    MGRSTARTDATE CHAR(9) );

11. Adding a column:
	ALTER TABLE EMPLOYEE ADD JOB VARCHAR(12);
    The new attribute will have NULLs in all the tuples of the relation right after the command is executed; hence, the
    NOT NULL constraint is not allowed for such an attribute

12. Adding a column with an unique, auto-incrementing ID:
	ALTER TABLE [table] ADD COLUMN [column] int NOT NULL AUTO_INCREMENT 	PRIMARY KEY;

13. Inserting a record:
  (Insert a tuple for a new EMPLOYEE for whom we only know the FNAME, LNAME, and SSN attributes)
	INSERT INTO EMPLOYEE (FNAME, LNAME, SSN)
  VALUES ('Richard', 'Marini', '653298653')

  (Attribute values should be listed in the same order)
  INSERT INTO EMPLOYEE
  VALUES ('Richard','K','Marini', '653298653','30-DEC-92', '98 Oak Forest, Katy,TX', 'M',37000,'987654321', 4);

14. MySQL function for datetime input:
	NOW()

15. Selecting records:
	SELECT * FROM [table_name];

  SELECT <attribute list>
  FROM <table list>
  WHERE <condition>

  SELECT BDATE, ADDRESS
  FROM EMPLOYEE
  WHERE FNAME='John' AND MINIT='B’ AND LNAME='Smith'

16. Explain records:
	EXPLAIN SELECT * FROM [table];

17. Selecting parts of records:
	SELECT [column], [another-column] FROM [table];

18. Counting records:
	SELECT COUNT([column]) FROM [table];

19. Counting and selecting grouped records:
	SELECT *, (SELECT COUNT([column]) FROM [table]) AS count FROM [table] GROUP BY 	[column];

20. Selecting specific records:
	SELECT * FROM [table] WHERE [column] = [value]; (Selectors: <, >, !=; combine multiple selectors with AND, OR)

21. Select records containing [value]:
	SELECT * FROM [table] WHERE [column] LIKE '%[value]%';

22. Select records starting with [value]:
	SELECT * FROM [table] WHERE [column] LIKE '[value]%';

23. Select records starting with val and ending with ue:
	SELECT * FROM [table] WHERE [column] LIKE '[val_ue]';

24. Select a range:
	SELECT * FROM [table] WHERE [column] BETWEEN [value1] and [value2];

25. Select with custom order and only limit:
	SELECT * FROM [table] WHERE [column] ORDER BY [column] ASC LIMIT 	[value]; (Order: DESC, ASC)

26. Updating records:
	UPDATE [table] SET [column] = '[updated-value]' WHERE [column] = [value];

  UPDATE PROJECT
  SET PLOCATION = ‘Galle', DNUM = 5
  WHERE PNUMBER=10

27. Deleting records:
	DELETE FROM [table] WHERE [column] = [value];

28. Delete all records from a table (without dropping the table itself):
	DELETE FROM [table]; (This also resets the incrementing counter for auto generated columns 	like an id column.)

29. Delete all records without deleting schema in a table:
	truncate table [table];

30. Removing table columns:
	ALTER TABLE [table] DROP COLUMN [column];

31. Deleting tables:
	DROP TABLE [table];

32. Deleting databases:
	DROP DATABASE [database];

33. Custom column output names:
	SELECT [column] AS [custom-column] FROM [table];

34. Export a database dump :
	mysqldump -u [username] -p [database] > db_backup.sql

35. Use --lock-tables=false option for locked tables.

36. Import a database dump:
	mysql -u [username] -p -h localhost [database] < db_backup.sql

37. Logout:	exit;

38. To eliminate duplicate tuples in a query result
  SELECT DISTINCT SALARY
  FROM EMPLOYEE
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Aggregate functions

1. Select but without duplicates:
	SELECT distinct name, email, acception FROM owners WHERE acception = 1 AND date >= 	2015-01-01 00:00:00

2. Calculate total number of records:
	SELECT SUM([column]) FROM [table];

3. Count total number of [column] and group by [category-column]:
	SELECT [category-column], SUM([column]) FROM [table] GROUP BY [category-column];

4. Get largest value in [column]:
	SELECT MAX([column]) FROM [table];

5. Get smallest value:
	SELECT MIN([column]) FROM [table];

6. Get average value:
	SELECT AVG([column]) FROM [table];

7. Get rounded average value and group by [category-column]:
	SELECT [category-column], ROUND(AVG([column]), 2) FROM [table] GROUP BY 	[category-column];

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Users functions

1. List all users:
	SELECT User,Host FROM mysql.user;

2. Create new user:
	CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

3. Grant ALL access to user for * tables:
	GRANT ALL ON database.* TO 'user'@'localhost';

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MySQL Mathematical Functions

1. Count rows per group	COUNT(column | *)

2. Average value of group	AVG(column)

3. Minumum value of group	MIN(column)

4. Maximum value of group	MAX(column)

5. Sum values in a group	SUM(column)

6. Absolute value	abs(number)

7. Rounding numbers	round(number)

8. Largest integer not greater	floor(number)

9. Smallest integer not smaller	ceiling(number)

10. Square root	sqrt(number)

11. nth power	pow(base,exponent)

12. random number n, 0<n < 1	rand()

13. sin (similar cos, etc.)	sin(number)

------------------------------------------------------------------------------------
MySQL String Functions

1. Compare strings	strcmp(string1,string2)

2. Convert to lower case	lower(string)

3. Convert to upper case	upper(string)

4. Left-trim whitespace (similar right)	ltrim(string)

5. Substring of string	substring(string,index1,index2)

6. Encrypt password	password(string)

7. Encode string	encode(string,key)

8. Decode string	decode(string,key)

9. Get date	curdate()

10. Get time	curtime()

11. Extract day name from date string	dayname(string)

12. Extract day number from date string	dayofweek(string)

13.Extract month from date string	monthname(string)

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#reset root password

sudo /etc/init.d/mysql stop
sudo mysqld_safe --skip-grant-tables &
mysql -u root
mysql> use mysql;
mysql> update user set password=PASSWORD("NEW-ROOT-PASSWORD") where User='root';
mysql> flush privileges;
mysql> quit

sudo /etc/init.d/mysql stop
sudo /etc/init.d/mysql start

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GITHUB
1.Adding an existing project to GitHub using the command line

1.Create a new repository on GitHub
2.Open Terminal
3.Change the current working directory to your local project.
4.git init
5.git add .
6.git commit -m "First commit"
7.At the top of your GitHub repository's Quick Setup page, click to copy the remote repository URL.
8.git remote add origin <remote_repository_URL>

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2.Changing a remote's URL

git remote -v
git remote set-url origin <git_url>
git remote -v // Verify new remote URL

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3. Everyday Use

1. shows you which files have been modified since the last commit
  $ git status

2. $ git add <filename>
(  if the file is untracked and you wish to add it to the project,
   git-add does it automatically for you.)

3. creates the new commit
    $ git commit -m "commit_msg"

4. can stored particular branch
    $ git push origin <branch_name>

5. getting the changes from the remote server, and merging them
   into the local tree.
    $ git pull
    (If conflicts occured should resolved, can view by git diff
    add file and again commit that file)

6. reviewing history
  $ git log

7. show commit content
   $ git show <commit_number>
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git branch

1. create a new branch
   git branch <branch_name>

2. checkout another branch
   git checkout <branch_name>

3.to delete a branch run from master branch
   git branch -d <branch_name>

4. merge branches run from master branch
   git merge <branch_name>

------------------------------------------------------------------------------------------------
Revert a commit



SYMFONY


Composer

1. Update all dependencies of current project
composer update

2. Install dependencies for current project with versions defined in composer.lock
composer install

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Console

1. List available commands and show the Symfony version
php app/console

2. Display help for given command
php app/console help [command]

3.  Display all configured public services
php app/console container:debug [--show-private] [service_name]

4. Dump all assets to the filesystem
php app/console assetic:dump

5. doctrine:schema:update
Update the database with its new schema. Use with --dump-sql and --force


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Cache

Clear the cached information
php app/console cache:clear

In Server
php app/console cache:clear --env=prod

(After clearing cache should set permission to execute following files)
sudo chmod 777 -R app/logs app/cache

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Bundle

Install bundles web assets under a public web directory
php app/console assets:install <target_dir> [--symlink] [--relative]

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Routing

Display current routes for application
php app/console router:debug | grep [router_name]

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Logger

$logger = $this->get('logger');
$logger->debug("===================================================================");


JITSI

JItsi locally setup in your computer---------------

1.git clone <the link>

2.sudo n lts (take the long term support version)

3.npm install

4.make

5 ./node_modules/.bin/webpack-dev-server // start the server

6. ./node_modules/.bin/node-sass css/main.scss css/all.bundle.css && ./node_modules/.bin/cleancss css/all.bundle.css >
css/all.css ; rm css/all.bundle.css // compile css


PM2

PM2 is a production process manager for Node.js applications with a built-in load balancer.
It allows you to keep applications alive forever, to reload them without downtime and to facilitate
common system admin tasks.

Install pm2
npm install pm2@latest -g

# Fork mode
pm2 start app.js --name my-api # Name process

# Listing
pm2 list               # Display all processes status

# Logs

pm2 logs [--raw]       # Display all processes logs in streaming
pm2 flush              # Empty all log files
pm2 reloadLogs         # Reload all logs

# Actions

pm2 stop all           # Stop all processes
pm2 restart all        # Restart all processes

pm2 reload all         # Will 0s downtime reload (for NETWORKED apps)

pm2 stop 0             # Stop specific process id
pm2 restart 0          # Restart specific process id

pm2 delete 0           # Will remove process from pm2 list
pm2 delete all         # Will remove all processes from pm2 list

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Add Another Mail Account To Gmail

gmail → setting → Accounts and Import → Add another email adress
smtp.zoho.com

zoho → settings → configure IMAP → click IMAP check box
verify and paste confirmation code
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FREEESWITCH

#Freeswitch terminal restart
fs_cli restart

#shutdown
fs_cli -x “shutdown”

#run freeswitch
1. sudo su
2. go to bin ==> cd /usr/local/freeswitch/bin
3. ./freeswitch

#Backing up and restoring your Raspberry pi’s SD card
df -h ==> show all the available space
again insert SD card and run ==> df -h
	/dev/mmcblk0p1
	/dev/mmcblk0p2

then terminal
sudo dd if =/dev/sdb of=~/SDCardBackup.img

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Vim

#Delete Multiple Lines
shift + v ==> Go to visual mode
Select necessary lines
delete

#Copy terminal output into file
1. triple-click the last line
2. hit shift + home
3. shift + click first line
4. copy ctrl +shift + c
You can then paste the content to other text document

NANO

#exit with save
Ctrl +X ---→ y --→ enter
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Angular2

1. Create Component Using Terminal
	ng generate component <component_name>


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REACT-NATIVE

#Run android project
react-native start
react-native run-android
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IMPORTANT  WEB PAGES

#Get know your screen resolution
whatismyscreenresolution.net