linux notes

 How to install openjdk on centos 8:

dnf search jdk

dnf install java-11-openjdk-devel.x86_64

Ref: https://www.liquidweb.com/kb/how-to-install-openjdk-11-on-centos-8/

create service centos:

ref: https://www.thegeekdiary.com/centos-rhel-7-how-to-make-custom-script-to-run-automatically-during-boot/

tomcat service create:

https://www.digitalocean.com/community/tutorials/how-to-install-apache-tomcat-8-on-ubuntu-16-04

deploy to container plugin is used for deploying to tomcat webapps from jenkins

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find . -name "kramer" --> search for kramer file starting from current directory

locate "kramer"

if "locate" command doesn't output any result, then as root run "updatedb"

Also make sure you have "mlocate" package installed.

To check = rpm -qa | grep mlocate

to install: yum install mlocate

difference between find and locate:

locate uses preloaded database and find seraches from file system.

passwd --> to change password of user

passwd <usernmae>

--

wildcard

* zero or more

? single character

[] range of characters

rm abc*

touch abcd(1..9)

ls -l ?bcd*

ls -l *[cd]*

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3 types of permissions

r read

w write

x executable

controlled at 3 levels each permission

u user=yourself

g group=can be people in sameproject

o other = eveyone on the system

ls -l

to change permission: chmod

chmod g-w jerry

file permissions:

https://www.tutorialspoint.com/unix/unix-file-permission.htm

2 owners of a file/directory: user and group

chown and chgroup

-R recursive

Access control list:

--to be continued

/etc/shells

types of shells:

--

Gnome --- graphical environment in linux

KDE -- 

sh

bash

csh and tcsh

ksh

shebang line:

#!/bin/bash

# comments

read name ---> saves input to variable name

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need to try today:

https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/postgresql_flexible_server