IPTABLES, Firewall, Actual Firewall + Security Group - AWS

https://www.tecmint.com/fix-no-route-to-host-ssh-error-in-linux/

https://www.cyberciti.biz/faq/how-to-list-all-iptables-rules-in-linux/                            

sudo nmap -p 6900,25,22,8080,21000,7856,9084 10.79.197.70

sudo iptables -S

sudo nmap -p 6900,25,22,8080,21000,7856,9084 10.79.197.70

https://www.e2enetworks.com/help/knowledge-base/how-to-open-ports-on-iptables-in-a-linux-server/#step-1-list-the-current-iptables-rules

sudo iptables -D IN_public_allow -p tcp -m tcp --dport 7856 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT

sudo iptables -A IN_public_allow -p tcp -m tcp --dport 7856 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT

Zscaler Private Access (ZPA) , CHATTR Linux, Immuable, VPC -> PrefixList

https://superuser.com/questions/1647896/putty-key-format-too-new-when-using-ppk-file-for-putty-ssh-key-authentication

VPC -> PrefixList
https://docs.aws.amazon.com/vpc/latest/userguide/managed-prefix-lists.html

https://aws.amazon.com/marketplace/pp/prodview-epy3md7fcvk4g?ref=cns_srchrow

https://www.fugue.co/blog/cloud-network-security-101-aws-security-groups-vs-nacls

https://www.javatpoint.com/aws-nacl-vs-security-group

https://mylearningsonline.com/aws-services/aws-vpc-security-group-nacl/

https://www.davidc.net/sites/default/subnets/subnets.html

http://www.cronmaker.com/

https://www.baeldung.com/linux/grep-sed-awk-differences#1-basic-syntax-1

chattr +i      [To make it immutable, Its not related to access permissions] - Change Attribute

SetUserBit

SetGroupBit                       chmod 2775          chmod +ug rw

which                                 Which executable

whereis

https://stackoverflow.com/questions/39239276/how-to-enable-a-directory-listing-in-apache-web-server

Azure Pipelines, YAML Schema

https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=azure-devops&tabs=schema%2Cparameter-schema

https://docs.microsoft.com/en-us/azure/devops/pipelines/get-started/key-pipelines-concepts?view=azure-devops

https://docs.microsoft.com/en-us/azure/devops/pipelines/repos/azure-repos-git?view=azure-devops&tabs=yaml#ci-triggers

https://faun.pub/reduce-your-build-time-using-caching-in-azure-pipelines-7a7bd0201cee

Resources

Trigger

Pipeline -> Stage(Implicit) -> Jobs -> Steps [Task, Script, Checkout]

jobs:

- job: Job_1

  displayName: Agent job 1   

  pool:

    vmImage: ubuntu-latest

  steps:

    -script: echo "Hello World"

pool:

  name: Default

  demands: SpecialSoftware # Check if SpecialSoftware capability exists

  

  

stages:

- stage: A

  jobs:

  - job: A1

  - job: A2

- stage: B

  jobs:

  - job: B1

  - job: B2  

https://docs.microsoft.com/en-us/azure/devops/pipelines/process/phases?view=azure-devops&tabs=yaml

stages:

- stage: A

# stage B runs if A fails

- stage: B

  condition: failed()

# stage C runs if B succeeds

- stage: C

  dependsOn:

  - A

  - B

  condition: succeeded('B')

If you choose to specify a pool at the stage level, then all jobs defined in that stage will use that pool unless otherwise specified at the job-level.

stages:

- stage: A

  pool: StageAPool

  jobs:

  - job: A1 # will run on "StageAPool" pool based on the pool defined on the stage

  - job: A2 # will run on "JobPool" pool

    pool: JobPool

jobs:

- job: Foo

  steps:

  - script: echo Hello!

    condition: always() # this step will always run, even if the pipeline is canceled

- job: Bar

  dependsOn: Foo

  condition: failed() # this job will only run if Foo fails

https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops&tabs=yaml

jobs:

- job: Debug

  steps:

  - script: echo hello from the Debug build

- job: Release

  dependsOn: Debug

  steps:

  - script: echo hello from the Release build

You can organize pipeline jobs into stages. Stages are the major divisions in a pipeline: "build this app", "run these tests", and "deploy to pre-production" are good examples of stages. They are logical boundaries in your pipeline where you can pause the pipeline and perform various checks.

Pipeline > Stages >Stage>Steps>Step

jobs:

- job: A

  steps:

  - bash: echo "A"

- job: B

  steps:

  - bash: echo "B"

  

  

  If you organize your pipeline into multiple stages, you use the stages keyword.

If you choose to specify a pool at the stage level, then all jobs defined in that stage will use that pool unless otherwise specified at the job-level

stages:

- stage: A

  jobs:

  - job: A1

  - job: A2

- stage: B

  jobs:

  - job: B1

  - job: B2

  

  When you define multiple stages in a pipeline, by default, they run sequentially in the order in which you define them in the YAML file. The exception to this is when you add dependencies. With dependencies, stages run in the order of the dependsOn requirements

  stages:

- stage: string

  dependsOn: string

  condition: string

  -----------------------------------------------------------

  You can organize your pipeline into jobs. Every pipeline has at least one job. A job is a series of steps that run sequentially as a unit. In other words, a job is the smallest unit of work that can be scheduled to run.

  

  In the simplest case, a pipeline has a single job. In that case, you do not have to explicitly use the job keyword

  

  jobs:

- job: myJob

  timeoutInMinutes: 10

  pool:

    vmImage: 'ubuntu-16.04'

  steps:

  - bash: echo "Hello world"

  

  

  /usr/lib/jvm/adoptopenjdk-11-hotspot-amd64

 # update-alternatives --config java

          update-alternatives --list java

          echo ls /etc/alternatives

          ls /etc/alternatives

  

  

https://docs.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml

https://faun.pub/reduce-your-build-time-using-caching-in-azure-pipelines-7a7bd0201cee

XARGS AWK CUT GREP

ls -l . | grep ^d | awk '{print $9}' | xargs rm -rf

ls -al | grep -E '^-.*ml'

ls -l | grep -E '^-.*ml' | awk '{print $9}' |xargs rm -f

https://www.thegeekstuff.com/2011/10/grep-or-and-not-operators/

https://stackoverflow.com/questions/16900945/bash-extract-string-from-text-file-with-space-delimiter/16901235#16901235

https://stackoverflow.com/questions/219402/what-linux-shell-command-returns-a-part-of-a-string

Linux Pending A-Z ::: Sudoers :: Login Shell : Non Login Shell :: Grep Regex :: Alias

sudo visudo

source /etc/sudoers

To put it very simple, it is “who where = (as_whom) what”.

https://medium.com/kernel-space/linux-fundamentals-a-to-z-of-a-sudoers-file-a5da99a30e7f

coraca ALL=ALL:ALL  /usr/bin/cat /etc/shadow

https://www.hostinger.in/tutorials/sudo-and-the-sudoers-file/

https://phpraxis.wordpress.com/2016/09/27/enable-sudo-without-password-in-ubuntudebian/

kk   ALL=(ALL)  NOPASSWD: ALL

user1 ALL=NOPASSWD: /bin/systemctl start vsts, /bin/systemctl stop vsts, /bin/systemctl restart vsts, /bin/systemctl status vsts

Using /etc/sudoers.d #

Instead of editing the sudoers file you can create a new file with the authorization rules in the /etc/sudoers.d directory.

https://www.garron.me/en/linux/visudo-command-sudoers-file-sudo-default-editor.html

https://www.linux.com/training-tutorials/configuring-linux-sudoers-file/

https://toroid.org/sudoers-syntax

https://medium.com/kernel-space/linux-fundamentals-a-to-z-of-a-sudoers-file-a5da99a30e7f

http://www.softpanorama.org/Access_control/Sudo/sudoer_file_examples.shtml

http://www.freekb.net/Article?id=269

https://www.hostinger.in/tutorials/sudo-and-the-sudoers-file/

https://www.tecmint.com/create-alias-in-linux/

https://linuxize.com/post/linux-xargs-command/

https://shapeshed.com/unix-xargs/

https://www.geeksforgeeks.org/alias-command-in-linux-with-examples/

https://www.techrepublic.com/article/linux-101-the-different-types-of-sudo-and-su/

https://www.blogger.com/u/1/blog/posts/2528866210673694202

https://unix.stackexchange.com/questions/384700/what-is-the-difference-between-su-username-and-sudo-su-username

https://unix.stackexchange.com/questions/38175/difference-between-login-shell-and-non-login-shell

https://linuxhint.com/list-only-files-not-directories/

https://medium.com/@rajsek/zsh-bash-startup-files-loading-order-bashrc-zshrc-etc-e30045652f2e

https://www3.ntu.edu.sg/home/ehchua/programming/howto/Regexe.html

https://regex101.com/

https://askubuntu.com/questions/815066/whats-the-difference-between-bashrc-and-etc-bash-bashrc 

Linux ENV Setings ---- /etc/profile /etc/bashrc ~/.bashrc ~/.bash_profile

export PATH=$PATH:/usr/local/bin/nodeSetup/

Any Folder Path we put on PATH is scanned for Executables

~/.bash_profile

~/ .bashrc

~/.profile

/etc/sudoers

/etc/yum.conf

/etc/os-release

/etc/hosts

/etc/hosts.allow

/etc/fstab

/etc/shells

/etc/passwd

/etc/group

/etc/shadow

/etc/profile

etc/bashrc      [/etc/profile.d]

/etc/bashrc          # Functions and aliases go in /etc/bashrc

/etc/profile            # System wide environment and startup programs, for login setup + Environment stuff (It sources/executes shell in /etc/profile.d)

/etc/profile.d        # It's much better to create a custom.sh shell script in  /etc/profile.d/ to make custom changes to your environment 

~/.bash_profile    # User specific environment and startup programs    #PATH=$PATH:$HOME/.local/bin:$HOME/bin       #export PATH --- It sources(executes)  ~/.bashrc

~/.bashrc              #Get the aliases and functions                                              

-----------------------------------------------------------------------------

/etc/profile file is used to set system wide environmental variables on users shells. 

/etc/profile is the system wide version of .bash_profile.

/etc/bashrc for Red Hat and /etc/bash.bashrc in Ubuntu is the system wide version of .bashrc.

.bashrc file in your home directory. 

This file is meant for setting command aliases and functions used by bash shell users

.bash_profile or .profile - in  your home directory.

These files are used to set environmental items for a particular user's shell

The difference is simple, 

/etc/profile is executed only for interactive shells 

/etc/bashrc is executed for both interactive and non-interactive shells.

-------------------------------------------------------------------------------

For User specific Stuff, You can put aliases in ~/.bashrc and ~/.bash_profile sources it , but ENV Paths etc should be put in ~/.bash_profile

For Stuff relevant to all , You should put stuff in custom shell inside /etc/profile.d 

https://shreevatsa.files.wordpress.com/2008/03/bashstartupfiles1.png

https://bencane.com/2013/09/16/understanding-a-little-more-about-etcprofile-and-etcbashrc/

The importance of using a login shell is that any settings in /home/user/.bash_profile will get executed.

Linux A-Z Gyaan

 https://www.digitalocean.com/community/tutorials/angular-query-parameters

https://www.concretepage.com/angular-2/angular-2-4-child-routes-and-relative-navigation-example#:~:text=Child%20routes%20can%20have%20their,outlet%2C%20children%2C%20loadChildren%20etc.&text=Router%20supports%20relative%20path%20using%20ActivatedRoute%20.

https://appdividend.com/2019/12/16/angular-form-control-example/

https://malcoded.com/posts/angular-custom-directives/

https://www.redhat.com/sysadmin/alternatives-command

https://access.redhat.com/solutions/505983#:~:text=PS1%20is%20a%20primary%20prompt,the%20%2Fetc%2Fbashrc%20file.

https://unix.stackexchange.com/questions/1373/how-do-i-switch-from-an-unknown-shell-to-bash#:~:text=You%20type%20in%20bash%20.,by%20editing%20%2Fetc%2Fpasswd%20.

https://www.freecodecamp.org/news/linux-command-line-bash-tutorial/

https://itsfoss.com/apt-vs-apt-get-difference/

https://askubuntu.com/questions/1190717/when-to-run-sudo-apt-update-and-when-sudo-apt-update-sudo-apt-upgrade

https://www.freecodecamp.org/news/symlink-tutorial-in-linux-how-to-create-and-remove-a-symbolic-link/

https://www.tecmint.com/remove-package-with-dependencies-using-yum/amp/

https://phoenixnap.com/kb/centos-uninstall-remove-package

https://stackoverflow.com/questions/29964042/how-to-remove-old-version-of-java-and-install-new-version

https://www.thegeekdiary.com/how-to-work-with-multiple-java-versions-under-linux/

https://www.lifewire.com/alternatives-linux-command-4091710

https://linuxize.com/post/how-to-add-directory-to-path-in-linux/

https://kb.iu.edu/d/acec

https://linuxhint.com/update_alternatives_ubuntu/

https://www.redhat.com/sysadmin/alternatives-command

https://www.digitalocean.com/community/tutorials/ssh-essentials-working-with-ssh-servers-clients-and-keys

https://www.ssh.com/academy/ssh/host-key

https://superuser.com/questions/437330/how-do-you-add-a-certificate-authority-ca-to-ubuntu/719047#719047

https://www.google.com/search?q=pem+linux+full+form&client=ms-android-oppo&sxsrf=ALeKk027xsSkCVYclkcJoeq4bbZA0X4big%3A1622683432717&ei=KC-4YK6gK_OM4-EPzOWZmAQ&oq=pem++linux+full&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAEYATIGCAAQFhAeMgUIIRCgATIFCCEQoAE6BAgjECc6BggAEAcQHjoICAAQCBANEB46BwghEAoQoAFQrghYoDZgxz5oAHAAeACAAYECiAG_F5IBBjAuMTAuNZgBAKABAcABAQ&sclient=mobile-gws-wiz-serp

https://www.tecmint.com/dpkg-command-examples/amp/

https://en.m.wikipedia.org/wiki/List_of_Linux_distributions

https://www.google.com/search?q=dnf+yum+difference&oq=dnf+yum&aqs=chrome.1.69i57j0l4.7585j0j4&client=ms-android-oppo&sourceid=chrome-mobile&ie=UTF-8

https://github.community/t/the-difference-between-forking-and-cloning-a-repository/10189

https://superuser.com/questions/740219/difference-between-apt-get-and-dpkg

https://www.tecmint.com/20-linux-yum-yellowdog-updater-modified-commands-for-package-mangement/

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sec-managing_yum_repositories

https://danielmiessler.com/study/fedora_redhat_centos/

https://itsfoss.com/centos-stream-fiasco/

https://blog.centos.org/2020/12/future-is-centos-stream/

https://unix.stackexchange.com/questions/52707/difference-between-chmod-775-and-chmod-2755

https://www.peachpit.com/articles/article.aspx?p=659655&seqNum=3

https://stackoverflow.com/questions/635869/can-yum-tell-me-which-of-my-repositories-provide-a-particular-package

https://www.cyberciti.biz/tips/how-do-i-find-out-what-shell-im-using.html

https://www.peachpit.com/articles/article.aspx?p=659655&seqNum=4

https://www.linuxfromscratch.org/lfs/view/9.1/chapter06/procps-ng.html

https://dzone.com/articles/how-to-edit-a-yaml-azure-devops-pipeline

https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=azure-devops&tabs=example%2Cparameter-schema

https://learnxinyminutes.com/docs/yaml/

https://docs.microsoft.com/en-us/azure/devops/pipelines/customize-pipeline?view=azure-devops

https://docs.microsoft.com/en-us/azure/devops/pipelines/build/ci-build-git?view=azure-devops&tabs=yaml

http://www.mattruma.com/create-a-single-build-release-pipeline-for-multiple-branches/