All About Linux

 File System

cd / It go to root dir. or main dir.

ls -ltr it show pre define folder or dir. shows

*Everything in linux is a File*

we used audio video in daily life that called file

but in linux command is also consider as a file

Whereis ls

cd /usr/bin

ls

All file avaible all commands avaible file also present

To manage all the data and file linux need a file system

Os store and manage data on disk or partitions using a

structure called filesystem

FileSystem includes files, directories and its related permissions.

Fs stores data in hierarchy of directories and files.

In Windows 

INSIDE THE FOLDER

LINUX FILE STRUCTURE

Types of file system/ versions

1. ext3 extended 3 

2. ext4

3. XFS

4. FAT

5. BTRFS etc..

How to check your linux filesystem?

lsblk -f

1. XFS (EXTENTS FILE SYSTEM)

XFS is 64bit high performance FS

support parallel I/O operations

works well with large files

<Which file we have to use>

its depends on application and user requirments

cd/ ----> root dirctory or main dir.

FS structure 

/boot   --> For butting OS  

/etc  ---> application config. file present system network ssh related file user file cong file also present

/usr/bin --> binaries file we not able to read bec, its present different format

switch from noraml to root user 

su -

cd/root/

/var --> system logs or applications logs presents 

for go /var

cd nginx/

ls -ltr

 

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Package Management 

use to install and remove software

Package files nothing but software files

Repositories

Trusted source repository

If you want to install anything we have repo. Trusted source

If admin update something he update into the repository 

Dependencies

Now the thing is that some of the package need other packages to work accurately.

A software is dependent on some other packages like one or more for 

the proper installation and working.

Insort it is a tool used to install and remove 

apt-get update ---> it install depencency automatically 

it a app store or playstore used to download software

2.for next apt-get upgrade ---> it upgrade 

3. apt-get clean --> it clean the cache data

4. apt-cache search (package name)

5. apt-get dist-upgrade --> it install kernal version

DPKG command

cat /etc/issue --> it show operating sytem

uname -a  --> package

dpkg -i zoom(app name)

apt-get update read

apt-get -f upgrade -->-f used to fixed broken files

dpkg -i (packagename)

zoom:- just write package name for installtion it working or not

dpkg --remove zoom :- for remove

dpkg -L zoom

to compley delete

Yum 

used for download dependency automatically

cd /var/log/

cat yum.log

yum update --> update and upgrade

yum check-update---> for check

yum install (package name)

yum install for multiple separted with commas

yum search gcc --> 

yum check-update telnet --> It show update msg

yum list samba

yum info samba

yum deplist samba --> depedecny list

yum list available-->

yum list available | grep httpd(name) --> used for filtering the data

yum installed

yum list all --> all list show

yum list kernel

uname -a

yum clean packages 

yum clean all

yum install httpd

yum remove httpd

yum grouplist

yum groupinstall "Netwrok"

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Linux user Management

for doing this we need root access

not normal access

super user / root user

id uid 0

how we can manage the user 

1 graphically

2. cmd

3. configtion file making changs

---

all user information present in etc/passwd (dir/file)

useradd (username)

ex useradd pranav

cat/etc/passwd --> all the user information present

----------

for comment

useradd -c "Pranav Kshirsa" pranav

man --> Manual

man useradd

----

usermod-> usermodify

usermod -c "pranav" pranav

--------

useradd user1 

userdel user1

userdel -r pranav

ls

-r all delete dirc. also delete

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Sudo Privileages

$- Normal user

# - Root user

 

Sudo super user privileges

sudo ---> forcefully switch to user

for admin access

sudo su root 

without password 

su ubuntu

sudo command is used to access restricted files and operations in linux os.

sudo cat >file1.txt

sudo mkdir dir1

 permission din

sudo -s

password

cat > file1.txt

exit --> back to normal user

su --> switch form one user to other

su root

root user not required password

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Cron Job

is a time-based job scheduler in Unix-like computer operating systems.

Schedule jobs to run periodically at fixed times,day,dates, or intervals.

1. crontab -l (to show all the current jobs)

2. Crontab -e (to edit or add new jobs)

website for checking

crontab.cronhub.io

create a file

crontab -e

(pwd)

21 16 * * * cd /home/ubuntu && ./create_file.sh

crontab -l  for list 

Output:--->

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Vi Editor

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Basic editor in linux

To create a file

i  - to go to insert mode

:wq  -- save and exit

:q!  -- exit without saving

Default mode - command mode

Esc - to come out of insert mode  to command mode

dd   - to delete a line

yy  --  to copy the line

p  - to paste  below

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Disk Management 

lsblk used to show disk block devices

sata s

nvme

1st alpha show type of disk and controller

2nd d means disk and last alpha show a means 1st b mean 2nd

ex sda

nvmr0n1

fdisk -l /dev/sda --> for particular

fdisk ---> for all disk

dmesg ---> disk message

dmesg | grep nvme --> for particular disk

lssw

when we normally delete only path deleted

badblocks -ws /dev/Sda(disk name)

#MBR = 4 primary partition

3 pri. 1 extended

fdisk -l /dev/sd  --> it show the partion of disk

 cat /proc/partitions

logical and extended partitions

lsblk -f

df ---> disk file

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How to create a partion

fdisk /dev/loop0

m

n

Partition type

   p   primary (0 primary, 0 extended, 4 free)

   e   extended (container for logical partitions)

Select (default p):

enter size

: +10M 

Mounting after creation of partion how linux will identify that the we used mounting

mount the device to the directory

mkdir/documents/

mount /dev/sdb1

mount -a --> eveything you did its working or not

if you want remove partion

we directly not remove we have 1st unmount it then remove

unmount/documents

rm -rf /documents/

Refer this link for more info.

https://youtu.be/cP1TqdOJNj8

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Service management

service is a group of process that run continusly on the background

and wait for a event to trigger

so service conitnusly lisen wait for a trigger to perform a task

Ex:- webhosting using apache

user asked for particular page 

TYPES:-

SSH 

NETWORK MANAGER 

ANYDESK

BLUETOOTH

 

To mange this service we need a program

EX:- 

systemctl status apache

systemctl start/stop/reload and restart

enable and disable you can do it

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Hard and Soft Link

what are link in linux ?

A connection between a file name and the actual data on the disk.

Ex:- desktop app icon and orginal file

we can call it a shortcut

Soft Link:-

Link will be removed if orginal file removed or deleted.

ln -s (path)/home/ubuntu/test (name)

Hard link

Renaming, deleting or removing the file will not effect the link

ln

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Networking in linux

a group of interconnet networking that are conneted to each other and sharing the resounce and file

Share resources across the network

communicate across the ntw with other users

1. Ifconfig & ping

to show the particular port 

ifconfig (package name)

1.enp-- ethernet connectivity

2.lo -- Local host

3.virb-- local ip address

to start and stop the internet connectivity

sudo ifdown enp

sudo ifup enp..

2. Ping 

to check the internet connection active or not

ping google.com

connected or not

to check other network connnected or not

communicate or not

3.

wget 

if you have a server and you want to download that file

$ wget<>

wget only do http and https

but

4.curl

it used for every single type

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Apache nginx install and configure 

steps

sudo apt-get install nginx

sudo apt-get install apache2

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