DAY7

Notes

Amazon keeps everything stored permanently even if the connectivity with putty is weak or disturbed(gets inactive)
smallest unit of HDD is sector
1 Sector = 512 bytes
minimum size of a partition is 512 bytes always
1kb = 1024 bytes = 2 * 512 bytes
Deleting or formatting Extended partition leads to loss of all logical partitions
Formatting does not mean Deleting data , it creates an environment for HDD to be understood by OS
Windows - NTFS(New Technology File System) , Red Hat - XFS , MAC - HFS+
common format mode is FAT and vfat - - > detectable on all OS
Format makes the index of HDD, inode table entry - empty
always partitions are formatted not HDD
mkfs. - > followed by double-taps shows all available extensions for format of hdd
/mnt # forlder made in linux where new HDD directory are created but not icon
/media # forlder made in linux where new HDD directory are created with icon
Popular Webserver is Apache which is free
Apache is the name of foundation with 3 products ~
1. apache httpd ( works for all)
2. apache apache2 ( works only ubuntu type OS)
3. apache TOMCAT (for JAVA)
LAMP - LINUX Apache Mysql PHP
NGINX is also a web server
IIS - internet information services - best for .net service providing and it is need to be purchased (from microsoft)
apache TOMCAT - most powerfull server for JAVA based web-site
IRCTC website works on NGINX
By default apache can run html websites
/var/www/html is the document root for your Apache
For task goto http://slashreboot.blogspot.com
for google search using python use googlesearch module
if need to do both read and write
1. r+ - > use when file is already created
2. w+ - > use when file is need to be created

To Attach a Volume

Open Instance in running state
Go to Volume section ad create ew hard disk
use 2 Gb volume size
select availability zone
create Volume
refresh
attach Volume

Linux Commands

$ fdisk -l # no of hdd attached to linux
$ fdisk -l disk-name # shows only the hdd with disk-name given
fdisk disk-name # enter in the disk
mkfs.xfs partition-name # mkfs - > make file system , xfs - > supportable format
$ df # disk free , shows the path of new partition or HDD mounted on OS
$ df -h # path of new partitions in human readable format
$ df -hT # shows format type
$ rpm -q package-name # package available to in system
$ rpm -qc package-name # query configuration
$ systemctl start package-name # start the service of your package
$ systemctl status package-name # check the status of your services

To Create partition in HDD

$ fdisk disk-name
type print or p #shows present partition if present
new or n # to create new partition
Select the type of partition primary = p ; extended = e
select primary partition and 1 partition
starting of the partition should be taken default
+size(unit) # example, +300M creates a 300MB size partition
to create last partition just keep on using default values to use complete HDD size

Never - Ever delete or format Extended partition

To create logical partitions,first needs to create extended partition then only logical partition will be made
q to quit without saving and wq to save

Format partition

mkfs.extension partition-name

Mount hdd

it occurs after ,
1. Partition creation
2. Format the HDD
if mounting an partition into an OS , the OS will create a folder at some random location and link with /tmp/newvolume which shows the icon on Desktop
Mount means creating a folder and map/link the partition
make a folder in /mnt #it will not make an icon
use the Command

mount /dev/xvdf1 /mnt/mypart

to make an icon, mount HDD in /media by making a folder in it

Make mounting permanent

* open /etc/stab
* at end write
  partition-name mount-folder format-type
* $ mount -a # checks if mounting is done properly

Server

Server is a kind of service provider example ~
1. Gmail - email Server
2. Youtube - streaming Server
3. Teacher - knowledge Server
4. Projector - visual server
Client is a service receiver and service is obtained after receiver request

Architecture

  many-client -  -  internet/network ---- (server)

web-server is one which provides a web-page

To deploy any server

Install software related to that server

$ yum install httpd # if not present in OS

Configure the changes --(do rquired changes) # no need for html
Start service

$ systemctl start httpd

* To start any service in Redhat use command to start any service, httpd replace by any services

Check for status using

$ systemctl status httpd

Deploy your own web-site

Create a web-package and save it in /var/www/html
On AWS allow http port from security part
Open a web-browser , in URL insert aws-ip/page-name

Directory / File Handling

things that can be done with a directory are : * create * delete * permission * rename * store * cp * cut * blank
work to do in file-Handling * permission - no need to Open * read - need * create - file need to be opened * append - need * write - need * delete - no need

OS module

* chdir = change Directory
* curdir = present working Directory

Day 7

MBR (Master Boot Record) In our old laptops we have by default bios loaders which means we have MBR installed. Since new releases have by default UEFi installed.

To list the disks attached in the system

Use the command lsblk to list the attached volumes

To list detailed view of hard drives

Use the command fdisk -l to list detailed view of drives.

[root@ip-172-31-43-73 ~]# fdisk -l
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.

Disk /dev/xvda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: gpt
Disk identifier: 477BBCC7-BB8A-408B-9778-8F4E6E46B138


#         Start          End    Size  Type            Name
 1         2048         4095      1M  BIOS boot
 2         4096     20971486     10G  Microsoft basic

Disk /dev/xvdf: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

To list detailed view of a selected drive

Use fdisk -l /diskname

[root@ip-172-31-43-73 ~]# fdisk -l /dev/xvdf

Disk /dev/xvdf: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

To get inside a hard disk

Use fdisk /drivename

[root@ip-172-31-43-73 ~]# fdisk /dev/xvdf
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xf5cce8b6.

Command (m for help): print

Disk /dev/xvdf: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xf5cce8b6

    Device Boot      Start         End      Blocks   Id  System

Command (m for help):

Create `new` partition

The smallest thing in a hard disk is sector which is a size of 512bytes. Now to create a new partition use the command new or n to create a new partition.

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p):

To create a primary partition in disk

By default we create a primary partition so in order to create a primary partition we have to press p in order to create a primary partition.

Select (default p): p
Partition number (1-4, default 1):

To start the first sector we have to enter the block value by default we have to press `enter`.

First sector (2048-4194303, default 2048):
Using default value 2048

Now we have to give size or number of sectors

To give size we use +300M to create a 300MB partition in the drive

Last sector, +sectors or +size{K,M,G} (2048-4194303, default 4194303): +300M

Again we have to create 2 more primary partitions total 3 primary

Command (m for help): n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p): p
Partition number (3,4, default 3):
First sector (1026048-4194303, default 1026048):
Using default value 1026048
Last sector, +sectors or +size{K,M,G} (1026048-4194303, default 4194303): +100M
Partition 3 of type Linux and of size 100 MiB is set

Now we have to create the last partition as extended partition.

Command (m for help): n
Partition type:
   p   primary (3 primary, 0 extended, 1 free)
   e   extended
Select (default e):
Using default response e
Selected partition 4
First sector (1230848-4194303, default 1230848):
Using default value 1230848
Last sector, +sectors or +size{K,M,G} (1230848-4194303, default 4194303):
Using default value 4194303
Partition 4 of type Extended and of size 1.4 GiB is set

Note never ever delete or format extended partition because it contains all of your logical partitions.

Now we will create our 1st logical partition.

Command (m for help): n
All primary partitions are in use
Adding logical partition 5
First sector (1232896-4194303, default 1232896):
Using default value 1232896
Last sector, +sectors or +size{K,M,G} (1232896-4194303, default 4194303): +250M
Partition 5 of type Linux and of size 250 MiB is set

Command (m for help): p

Disk /dev/xvdf: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xcff9d12c

    Device Boot      Start         End      Blocks   Id  System
/dev/xvdf1            2048      616447      307200   83  Linux
/dev/xvdf2          616448     1026047      204800   83  Linux
/dev/xvdf3         1026048     1230847      102400   83  Linux
/dev/xvdf4         1230848     4194303     1481728    5  Extended
/dev/xvdf5         1232896     1744895      256000   83  Linux

Now to save the partition system we have to use `wq` to save and exit the partition system

Command (m for help): wq
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@ip-172-31-43-73 ~]#

Now we have created partitions now we need to format the partitions in order to make it understandable to Operating system

Formatting a system means making enviorment, when we format a drive it cleans the Inode table index, this doesn't means that we have deleted the data from the hard drive.

NTFS New technology file system. This is for Windows Users
HFS+ This is for Apple users.
XFS This is used for RedHat OS.
FAT / VFAT / eXFAT It is the common file system which works on all Operating Systems.

To format a partition

When we need to format the partition with XFS for our redhat system. Therefore we use

[root@ip-172-31-43-73 ~]# mkfs.xfs /dev/xvdf1
meta-data=/dev/xvdf1             isize=512    agcount=4, agsize=19200 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=76800, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=855, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

To check how many format file systems are available in your system

Press mkfs. and press double Tab to get the available file systems in your system.

[root@ip-172-31-43-73 ~]# mkfs.
mkfs.btrfs   mkfs.cramfs  mkfs.ext2    mkfs.ext3    mkfs.ext4    mkfs.minix   mkfs.xfs

Now we need to Mount our drive in order to use that.

When we mount a drive we basically create a folder and we map the partition with the folder. When we mount it assigns a icon to the folder which looks like a drive attached.

Basically mount means create a folder and map/link a partition.

To check the mounted disks we use the command `df`.

[root@ip-172-31-43-73 ~]# df
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/xvda2      10473452 1802012   8671440  18% /
devtmpfs          484748       0    484748   0% /dev
tmpfs             506948       0    506948   0% /dev/shm
tmpfs             506948   13280    493668   3% /run
tmpfs             506948       0    506948   0% /sys/fs/cgroup
tmpfs             101392       0    101392   0% /run/user/1000
tmpfs             101392       0    101392   0% /run/user/0

Now Create a folder in /mnt/drivename and then mount the partition. Check the exit code with echo $?

[root@ip-172-31-43-73 mnt]# mount /dev/xvdf1 /mnt/mydrive300size/
[root@ip-172-31-43-73 mnt]# echo $?
0

In order to check the drive in human readable format use `-h` and with format `-T`

[root@ip-172-31-43-73 mnt]# df -hT
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/xvda2     xfs        10G  1.8G  8.3G  18% /
devtmpfs       devtmpfs  474M     0  474M   0% /dev
tmpfs          tmpfs     496M     0  496M   0% /dev/shm
tmpfs          tmpfs     496M   13M  483M   3% /run
tmpfs          tmpfs     496M     0  496M   0% /sys/fs/cgroup
tmpfs          tmpfs     100M     0  100M   0% /run/user/1000
tmpfs          tmpfs     100M     0  100M   0% /run/user/0
/dev/xvdf1     xfs       297M   16M  282M   6% /mnt/mydrive300size

Now we have mounted the partition but its icon is not visible. So if you need icon then create a folder in `/media/partitionname` insteed of `/mnt/partitionname`.

Mounting a partition in media folder will automatically create a icon for that.

Now we need to create permanent entry for mounting the drive.

There is a file in /etc/fstab which is used to automount the drive.

/dev/xvdf1 /mnt/mydrive300size XFS

Client and Server Architecture

Server is a service provider which responds on a request generated by a client.
CLient is service reciever which request from server to get its response by server.
The server which serves web pages is called as web server.
The most popular web server on internet is Apache httpd and Apache apache2
httpd works on every operating system.
apache2 works on Ubuntu or linux systems.
NGINX is also a popular server. Example IRCTC Website works on NGINX
IIS is a specialized server which works best for Dot net based serves.
TOMCAT is a apache server which works best on JAVA based websites for streaming. It is specifically configured for JAVA websites.

To check a software is installed on RedHat or not.

Use the command rpm -q package_name to check that the package is available or not.

To check software configuration file of a package.

Use the command argument -c like rpm -qc package_name

[root@ip-172-31-9-238 ~]# rpm -qc httpd
/etc/httpd/conf.d/autoindex.conf
/etc/httpd/conf.d/userdir.conf
/etc/httpd/conf.d/welcome.conf
/etc/httpd/conf.modules.d/00-base.conf
/etc/httpd/conf.modules.d/00-dav.conf
/etc/httpd/conf.modules.d/00-lua.conf
/etc/httpd/conf.modules.d/00-mpm.conf
/etc/httpd/conf.modules.d/00-proxy.conf
/etc/httpd/conf.modules.d/00-systemd.conf
/etc/httpd/conf.modules.d/01-cgi.conf
/etc/httpd/conf/httpd.conf
/etc/httpd/conf/magic
/etc/logrotate.d/httpd
/etc/sysconfig/htcacheclean
/etc/sysconfig/httpd

To start a service or check status of a service in redhat

Use the command systemctl start service_name
Use the command systemctl status service_name

[root@ip-172-31-9-238 ~]# systemctl start httpd
[root@ip-172-31-9-238 ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sun 2019-06-09 06:15:23 UTC; 5s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 1391 (httpd)
   Status: "Processing requests..."
   CGroup: /system.slice/httpd.service
           ├─1391 /usr/sbin/httpd -DFOREGROUND
           ├─1392 /usr/sbin/httpd -DFOREGROUND
           ├─1393 /usr/sbin/httpd -DFOREGROUND
           ├─1394 /usr/sbin/httpd -DFOREGROUND
           ├─1395 /usr/sbin/httpd -DFOREGROUND
           └─1396 /usr/sbin/httpd -DFOREGROUND

Jun 09 06:15:23 ip-172-31-9-238.ap-south-1.compute.internal systemd[1]: Starting The Apache HTTP Server...
Jun 09 06:15:23 ip-172-31-9-238.ap-south-1.compute.internal systemd[1]: Started The Apache HTTP Server.

Now we need to add the code of our html page.

So we have code in our github and we can clone that code in /var/www/html/
Now by default we dont have git installed so install git yum install git
Now clone the webpage you want and just use the folder path and run that.

File Handling in Python

There are some operations we perform in file handling.

create
delete
rename
store
permission
Copy
Cut
blank

Example code to search time functions in time liberary

import time
x=[]
for i in dir(time):
    if 'time' in i:
        x.append(i)

y = [i for in dir(name) if 'time' in i]

import os
[j for j in dir(os) if 'dir' in j]

os.mkdir('hellololllloooo)
os.rmdir('ubfibjv)

chdir it means cd curdir it means pwd chmod it means chmod mkdir it means mkdir

To open a file we have a function open()

f = open('hello.txt','w')

To write a file we have a function write() in python call this will file handle.

f = open('hello.txt','w')
f.write("Hello world this is file writer")

To close a file we have

f = open('hello.txt','w')
f.write("Hello world this is file writer")
f.close()

To apply both read and write operations we use w+
When we write or read something python cursor shifts.
To fix this issue we have a function seek() this is used to get the curson position by entering the integer value of the position
To open a file in append mode use the mode a while opening the file.
- Since this is to add the data you cannot read the data.
To perform both read and write operations then use a+ to perform read and write operations.

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