daws-88batch-notes/session-04.txt at main · iamnireesh/daws-88batch-notes · GitHub

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1. file or directory not found -> refer the key either by absolute or relative path
2. SG check inbound and outbound rules..
	All traffic All ports source 0.0.0.0/0
3. key pair, while importing no new line

uname -> system information
ls -ltr -> latest files at the bottom in long format
ls -la
touch
cat -> read or enter the text
cat >
cat >>
rm
rmdir -> remove directory
cp
mv
head and tail
wget
curl
grep -> search for the content
cut and awk

cut -d ":" -f1
awk -F "" '{print $NF}'

awk -F ":" '$3>=1000 {print $1, $3}'

vim editor -> visually improved

vim <file-name> -> open the file
create and open the file

colon mode
===========
:q -> quit
:wq -> save the file
:q! -> dont save any changes, force quit
:set nu -> display numbers
:<line-number> -> cursor goes particular line number
:/<word-to-search> -> top to bottom
:?<word-to-search> -> bottom to top
:<line-number>d -> deletes that line
:%d -> delete everything
:noh -> dont highlight
:<line-number>s/<word-to-find>/replace-word -> replaces first occurence
:<line-number>s/<word-to-find>/replace-word/g -> all occurences
:%s/<word-to-find>/replace-word/g -> all occurences in all lines

Esc Mode
=========
gg -> takes to top of the file
shift+g -> takes us to bottom of the file
u -> undo
ctrl+r -> redo
dd -> deletes the line
yy -> copy the line
p -> paste below that line
shift+p -> paste above that line


User Management
===============
user group roles permissions

user -> human
group -> group of humans, team
roles -> position
permissions -> access level to that roles

CRUD

-> user create
-> create group/team
-> assign user to that group

-> remove user from group
-> delete user

useradd <user-name>
id <user-name>
cat /etc/passwd -> all users info
cat /etc/group -> display all the groups in server

A user in Linux will have only one primary group and atleast one secondary group

when you create user, group also will be created with same name

groupadd devops

usermod -g <group-name> <user-name>
usermod -g devops ramesh
usermod -aG testing ramesh

passwd ramesh -> set the password

by default only key-based authentications are enabled

/etc/ssh/sshd_config -> ssh configs are here
sshd -t -> check the syntax of config

How to give sudo access to user

/etc/sudoers

gpasswd -d <user-name> <group-name>

.zip -> windows zip format
.tar.gz

tar -cf <file-name>.tar.gz <folder>
tar -xf <file-name>.tar.gz

1. lock him immidiately
2. remove from all groups
3. take backup of his home folder
4. delete the user

userdel -r ramesh -> remove user ramesh and his home directory