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DAY 28.md

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DAY 28

In exam , two virual machines will be provided , so perform tasks as specified

  • 122 is ip given by virtual machine when its connected with Base OS and its not accessible to all world
  • World cannot directly access virtual machine , the network is accessed through Base OS
  • always create password through passwd command only -- no reason
  • crontab doesn't show actions or output of some command on terminal so it can be checked using I/O redirection
  • watch date is command to start clock
  • always restart service after changing config file of any services
  • to install new kernel
rpm -ivh ftp-address-of-kernel-location    i - > install , u - > update
  • kernel installation process takes time so when this command is run ... wait until hostname is available to you by default ctrl C is prohibited in this action
  • to check kernel when reboot is done .... more then 2 lines will be seen for kernel
  • selinux is always updated only after reboot
  • after reboot selinux relabels all files and gets persistent

Enable IP Forwarding

* It is a feature of router with help of which ip of different series are able to communicate with each other
* two lan cards can communicate with each other when its ON
* run command
```
sysctl -a | grep -i ip_fo
```
* set net.ipv4.ip_forward = 1
* to make ip forwarding permanent,open
```
vim /etc/sysctl.conf
```
* write at end of sysctl.conf file
```
net.ipv4.ip_forward = 1
```
* to load new settings - > reads the sysctl.conf file and updates
```
sysctl -p
```
* 0 - > Disable    1 - > Enable
* to set it temporarily
```
sysctl net.ipv4.ip_forward = 1
```

Archive

* for gzip  --z  --gz
```
tar -cvzf file.tar.gz file-to-make-tar
```
* for bzip2
```
tar -cjvf file.tar.bz2 folder-name
```
* for xz
```
tar -cJvf file.tar.xz folder-name
```
* to decompress files elsewhere, copy the tar in that directory and decompress it by
```
tar -xvf tar-name
```
* to decompress at certain path
```
tar -xvf tar-name -C path-name
```

VDO -> Virtual Data Optimizer

* Minimum space requires = 15 to 20 GB
* maintins the copy of two or more copies
* the virtual size remains same and not increases even if same file is copied in the same folde again and again
* it is a optimizer and maintains if data is not duplicated
* for repo  requires
```
baseurl=AppStream and BaseOS
```
* repo link will be provided by the examiner
* for installation
```
yum install vdo kmod-kvdo
```
* it is not a service
* to create a vdo
```
vdo --create --name=vdo1 --device=/dev/vda --vdoLogicalSize=50G
```
* logical size can be greater then actual block device
* it is an dev mapper technology device <b>DM</b>
* to get information about vdo device
```
vdo status --name=particular-vdo-name
```
* to get all vdo devices list
```
vdo status
```
* to get list of vdo devices, uses 4GB for meta-data
```
vdostats --human-readable
```
* saving % denotes the amount of duplicated data
* to format
```
mkfs.xfs /dev/mapper/vdo1
```

Computer Vision

Ideas

* find specific keyword from a book and filter within 1~3 seconds
* search an object in an image / video
* find moving direction of object like animal or human
* find depth or distance from image capture
* face recognition (using LBpH with opencv , for more accuracy use dlib library available in DL)
* using face_recognition library made by facebook i coordination with dlib, face can be easily recognized ( need high cpu and gpu)
* YOLO - > you only look once -> tech used in face recognition mobile which gives 90+ accuracy for face_recognition with single image
* Kairos (no need to code)

Regression

  • Regression is used in situations where the result is predicted based on datasets of various situations
  • it is of 3 types:
    1. Linear Regression y = mx + c y-> outcome(dependent variable) x -> input(independent variable)
    2. Polynomial
    3. Logistic Regression(used in DeepLearning)

Linear Regression

* It is of 2 types
  1. Singular independent variable equation ~ y = mx + c
  2. Multiple independent variable equation ~ y = mx+ c + m1x1 + m2x2

tasks

  • live cricket data (web scrap) in csv format and store in html folder
  • find player record - > no of balls -> runs (batsmen)
  • draw a linear model for no of balls and runs