**AUTOSUGGESTIONS**
for autosuggestions before typing full words:(check web for more accurate description)

apt-get install zsh
apt-get install zsh-syntax-highlighting
apt-get install zsh-autosuggestions
cp ~/.zshrc ~/.zshrcbackup
echo "source $(dpkg -L zsh-autosuggestions | grep 'zsh$')" | tee -a ~/.zshrc
echo "source /usr/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh" | tee -a ~/.zshrc
source ~/.zshrc
nano ~/.bashrc

add exec zsh after #for examples in the third line and save

**oh-my-zsh**
After you have zsh, you will observe that there won't be automatic saving of history, or you won't
see your pwd as prompt. You can use oh-my-zsh (search on github) as an alternative.

sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

**CUSTOM PROMPT**
If you want to change the prompt, follow the below steps.
echo $PROMPT (will show you the current prompt)

First comment out the line saying ZSH_THEME="robbyrussell", because custom prompt was not working if 
there is a theme.
Go to .zshrc file present in home/$user/, there add this line anywhere.
PROMPT="%(?:%{%}➜ :%{%}➜ )%m@%T-%{%}%c%{%}:"
or
PROMPT="%m@%T-%B%30<..<%~%b %(!.#.>)"

Both of these prompts will give the same output, which will look like:
user@time-pwd: which will be like pi@13:35-tools:

One cool prompt I use will be of this form:

┌──(kali㉿kali - 19:27)-[~]
└─$ whoami
sherl0ck

The prompt for this appearance is: 

PROMPT="%F{%(#.blue.green)}┌──${debian_chroot:+($debian_chroot)─}${VIRTUAL_ENV:+($(basename $VIRTUAL_ENV))─}(%B%F{%(#.red.blue)}%n㉿%m %T%b%F{%(#.blue.green)})-[%B%F{reset}%(6~.%-1~/…/%4~.%5~)%b%F{%(#.blue.green)}]
└─%B%(#.%F{red}#.%F{blue}$)%b%F{reset} "

**RUNNING SOMETHING ON EVERY BOOT OR TERMINAL OPEN**
If you want to run some custom script every time the device boots up or every time a new terminal opens,
lets say a python script test.py at /home/<usr>/test.py.
Just add a new line to the ending of .bashrc or .zshrc (whatever your default shell is)

echo Running at boot...
sudo python /home/pi/test.py

You can also use crontab -e and add the command in the end to run it. You can also customize the time.
You can use "https://crontab.guru/" to know more abot the timing of crontab.

*/1 * * * * sudo python3 /home/sherl0ck/env/logtool/log-reader.py

If you want to know about a particular program or command:
whatis - A short single line description of what the command does.
man - This provides a complete manual of that progam.
apropos - Searches the manual page descriptions for a specified string. (apropos -a password change)