Devops_IntroLinux.txt

Why Org. needs DevOps:
 Fast Delivery,Higher Quality,Less capex+opex,Reduced Outage.

	#SDLC#
  Developers->Build----->.exe
   (git)      (Maven)      |
		         Test
		           |
		          Q.A 
		           |
		      Deploy(Onsite)(chef/ancible/docker/puppet)
		           |	    
		      Maintainance+(employee Training)
		           |
		       Monitoring(NagiOs,AWS cloud Watch)

..........................................

SDLC::
	Develop->BUild->Test->Q&A(Developer)
	Deploy->Maintanince->Monitoring()




DevOps Stages:

->version control::maintains version of code.(Git)

->continous Integration::compile,validate,review,unit testing,Integration testing

->continous Delivery:: deploy the build app to test servers

->continous Deployment:: deploying the test app on prod. server for realease



Devops is a methodology that allows a single team to manage the entire application
development life cycle that is development,testing,deployment and operations.

Agile drawback-Silos(employees not coperate)
Agile(Build short,Build often)(sprints)
(scrum)

	code                      deploy
build		plan        	         operator
			release	    
         test      		  monitor



-------------------------------------------------------------
			::Linux::


	UNIX:
	UNICS:uniplexed information and computing services
	
	unix v6-1975


	unix--  IBM-AIX
	        Sun Solaris
		Mac os
		Hp-Ux
		Linux(1991)

	Linux+GNU=OS
	(kernel)[part of os]

	LINUX -----> RHEL,Fedora,Debian,Others(ubuntu,centos,amazon linux,Kali Linux)

->Linux is not a unix derivative.It well written from scratch.
->Linux distribution is the linux kernal and collection of software together, create an OS.

Features:
	open source,secure,simplified updates for all feature software
	light weight,multiuser,multi distribution.

 File System hirarchy:
	/home= home directory for other user
	/root= its home directory for root user			  
	/boot= Its contains bootable files
	/etc = It contains all conf. files
	/usr = by default soft. installed in this.
	/bin = Its contains all commands used by user.
	/sbin= Its contains commands used by only root user.
	/opt = Optional application soft. packages.
	/dev = essential device files,this includes terminal
		devices,usb or any device attached to systems.
 	

	How to create a file:
	Cat Touch Vi/Vm  Nano
			(editors)	
		
	cat > filename
	touch file1 file2[empty file]
	
	sudo su=sudo user do switch user

	[root@ip]#
	
	case sensitive write all in small

CAT:    cat command is one of the most universal tools, yet all
	it does is copy standard input to standard output.

	create file .............ctrl+d[exit from file]
        copy files
	concatenate file
	tac
	
	cat > filename
	cat >> filename //add some content to existing files
        cat file1 file2 > all
	cat file1>file2 //copy
	
Touch: [timestamp]
	create a empty file
	create multiple empty file
	change time stamp of file
	update only access time of file,modify time of file.

 ex:
	touch file1
	ls
	touch file1 file2 
	ls
	stat file1
	touch -a file2(access time change)
	touch -m file2(modify time change)

	(meta data will change any changes on access and modify)

Vi Editor:
-A programer text editor
 vi filea
 insert i
 	----hello-----
 esc + (:wq or :x) , :q , :q!
 H J K L or directly arrow button(for navigate)
 

Nano:
nano fileb
ctrl+x(to out of file)

ll or ls -l(long listing of all file)
ls -a(hidden files)

history(all commands)

.....................................................

mkdir dirName(make a directory)
cd dirName(change directory)
cd ..(Parent directory)
pwd (present working directory)

touch .file('.' helps to hidden file)
mkdir .dirName(hidden directory)

cp <srcFile> <destFile>
mv <srcFile/dir> <dir>

mv oldFile newFile(rename)
rmdir delete directory
rm delete file

rmdir -p (remove parent and child)

rm -rf(forcefully delete)
rm -rp(remove non empty incuding parent and child)
rm -r(remove empty directory)


less file1
head file1
tail file1
more file1

...................................................

useradd ram(add user)
cat etc/passwd

groupadd myGroup
cat etc/group

gpassword -a sai myGroup
gpassword -m anamd,yash,saleem myGroup


ln -s file1 softFile
ln file1 hardFile

tar [clubing all files in single files]

	tar cvf dirx

gzip [compress] 
	gzip dirx.tar

gunzip 
	dir tar.gz

wget <url>(download any file)



-yum install tree
-mkdir -p dirx/diry/dirz

-useradd karri
-cat /etc/passwd
-groupadd myGroup
-cat /etc/group

-useradd dilip
-useradd sanjay

-gpasswd -a karri myGroup
-gpasswd -m dilip,sanjay myGroup

-cat /etc/group

-cat >> file1
-ln -a file1 softLinkFile1
-ls -l

-cat softLinkFile1

-ln file2 hardLink2

[hardlink normal kind of file]
-cat >> hardLink2
-cat file2


-softLink vs HardLink

-tar -cvf dirx.tar dirx
           (dest)  (src)

-gzip dirx.tar [compress]

-gunzip dirx.tar.gz

-tar -xvf dirx.tar 

-wget <url>
-ls
-yum install <fileName>

-rm -rf *(remove all files)
-------------------------------------------------------------------
Access Mode/Permission

	r 4 to display the content      to list content
	w 2 to modify 			to create or remove	
        x 1 to execute			to enter into directory
	
	

	10 character long:
	-/d/l rwx r_x r__ 
	(file/directory/link) (root user/admin) (group) (other users)



	-/d/l rwx r_x r__  1 root root 0 date time name
			   (symb. link) (owner) (group) (filesize)

	

	commands:
		[rwx(4+2+1)=7]
	
		chmod 777 dirName

		u=root user/owner,g=group,o=other
                + add, - remove, = assign permission 
		u+w(add write permission to user)
	1. chmod -> used to change access mode of file.
			chmod u-w,g+w,o=wx fileName
	2. chown -> change the owner.
			chown karri file1

	3. chgrp -> change the group.
			chgrp myGroup file1

chmod 777 dir1
chmod 755 file1

chmod g=r,o=rw dir1
chmod u=r,g=rwx,o=x file1

chmod u+w,g-w,o+r file1

chown karri dir1
chgrp linux file1