Abhishek S. Sharma

Posted on Aug 22, 2020

Linux - I am Love with Terminal

#linux #docker #ubuntu #bash

Forget your bird, Love Linux

Click on playground and roll on your sleeves :c) -

playground

There are four types of the shell, we have in Linux-

Broune Shell -Sh shell
C Shell - csh or tcsh
Z shell -zsh
My Favorite - Bourne again shell -bash
To check shell type-

echo #SHELL
To print on the terminal

echo Hi from terminal !!
To view the current directory, display absolute path, means path from the root

pwd
To view all the files in a directory, -a will display hidden files as well

ls
ls -a
To change directory, it is case-sensitive, and you have to type in the name of the folder exactly as it is.

cd .. - To go back from a folder to the folder before that
cd my_directory - to goto my_directory folder
When folder name has space e.g. my bird

cd my\ bird
Create a new directory

mkdir abhishek
When folder name has a space e.g. abhishek sharma

mkdir abhishek\ sharma
make directory hierarchy from one command

mkdir -p /dir_1/dir_2/dir_3/dir_4
Run multiple commands in a single line

cd abhishek\ sharma; mkdir devops_tools; ls
Create a file

touch file_1.txt
Write content in the file

cat > file_1.txt
write anything, write- "this is my first file in Linux" and type Ctrl+d to save
another way to do it

echo "this is my first file in linux" > file_1.txt
View content

cat file_1.txt
Remove directory and file commands

mkdir removable_dir
rmdir removable_dir
mkdir removable_dir
cd removable_dir; touch removable_file.txt
rmdir removable_dir
---it gives you an error
Notes: only blank directories can be deleted with rmdir; to delete a directory, which has content in it, we will use rm -r

rm -r removable_dir
To delete a file

rm file_1.txt
Copy commands-
Copy a file to another file

cp {options} source_file target_file
cp new_file.txt copy_file.txt
Copy File(s) to another directory or folder

cp {options} source_file target_directory
touch /dir_1/dir_2/file_4.txt
cp -v /dir_1/dir_2/file_4.txt /dir_1/dir_2/dir_3/dir_4
Copy directory to directory

cp {options} source_directory target_directory
To copy a directory from one place to another use -r or -R option in cp command

cp -r /dir_1/dir_2/dir_3/dir_4 /dir_1/dir_2/
If the destination directory already has the same file, still you want to copy that file, to overwrite it use *-i*

cat > dir_1/dir_2/file_4.txt - this is me. press ctrl+d
cp -i /dir_1/dir_2/file_4.txt /dir_1/dir_2/dir_3/dir_4
Move command- mv command to move the files one place to another

touch dir_1/dir_2/file_3.txt
mv -v dir_1/dir_2/file_3.txt dir_1/dir_2/dir_3
Rename filename

touch latest.txt
want to change this file name latest to new

mv latest.txt new.txt
rm latest.txt
Search something

locate new.txt
if you want to ignore the case

locate -i New.txt
if you want a file that has the word "this"

locate -i this
If you want the file(s) that has words "this" and "me"

locate -i *this*me

To view available disk space

df
above command will show disk space in KB, to view in MB use the following command
df -m

To view disk usage by files

du
to view disk space used by a directory

du dir_1
To view Linux distro

uname
uname -a
Package manager apt-get

sudo apt-get update
sudo apt-get install nginx -y
To view your IP and name in host or network

hostname
hostname -I
To know your user account

whoami
To view user id, group id, group etc.

id
Download a file from a link

curl www.randomlink.com/downloadable-file.txt -O
OR
wget www.randomlink.com/downloadable-file.txt -O downloadable-file
Service start/stop/enable/disable/restart/status

systemctl status nginx
systemctl restart nginx
systemctl stop nginx

systemctl status nginx
systemctl start nginx
systemctl disable nginx
systemctl enable nginx
To check connection to server

ping {ip address}
ping www.google.com

Bonus to read

Write clear to clean the terminal.
to autofill use TAB. Suppose you have a folder- my_folder and want to go to that folder, You just need to type cd my and then TAB and the terminal fills the rest up and makes it cd my_folder.
To stop a command write Ctrl+C
to force stop a command write Ctrl+Z
Write exit to exit from terminal

Top comments (30)

Louis Low • Aug 22 '20

When a file size increasing overtime, use truncate, but without changing anything to the file permission and other stuff that applied to it. Best with adding it to crontab.

-s is set limit file size e.g. 1024k

$ truncate -s 1024k /var/log/kern.log

Vlastimil Pospichal • Aug 23 '20

Unfortunately, this shortens the end of the file, which reduces its usability.

Louis Low • Aug 23 '20

Luckily, you can set limit the file size.

Vlastimil Pospichal • Aug 23 '20

When logging in, I am not interested in the beginning of the file, but mainly its end. Every time I cut it off, logging loses its meaning.

Louis Low • Aug 24 '20

You are right. For user does not care about the logging but just want to reduce the file size (a couple of gigabytes). This is useful.

Raphael Habereder • Aug 22 '20 • Edited

Pro Tip: never use rm -r directory/
You will get used to it, and one day you will use env-vars and use rm -r $someDir

That is when bad things can happen. Especially if $someDir ends up being / for some reason.

If you delete something recursively, be precise. If you want to prevent deleting any important directory, there is a neat trick.

Get used to rm -r directory/* && rmdir directory/ and
create a file named -i in all directories you want to protect. This can be done using
touch -- -i
or
touch ./-i

The * in rm -r directory/* will expand the -i File to the command line, so your command ultimately becomes
rm -rf -i
Thus rm will prompt you before deleting anything. You can put this file in your /, /home/, /etc/, and so on.

rhymes • Aug 23 '20

what if you simply alias rm with a "trash" tool that puts stuff in your desktop Trash can?
Or in alternative, alias rm with rm -i ?

Raphael Habereder • Aug 23 '20

That could be a solution. I never really used "~/.local/share/Trash/" before.
rm in linux means "it's gone for good now". I'm not sure if rm has a "soft delete" or anything of the likes. The only thing to revert a rm is to restore a backup afaik.

I'm not a fan of aliasing rm, since aliases are user-only and if you don't keep your alias file portable on you for every system, through git or whatever, you rely on it on the wrong machine, and your stuff is gone.
rm should always be used with caution.

rhymes • Aug 23 '20

I don't use Linux but in macOS terminal I have the following alias in my .zshrc:

rm='trash -i'

where trash is hasseg.org/trash/

Never been happier :D

Raphael Habereder • Aug 23 '20

That's a cool little utility for my mac! I'll be sure to try that one, thanks! :)

omar • Aug 23 '20

thank you pal..that was helpful :)

Raphael Habereder • Aug 23 '20

Gladly! I hope you will continue to enjoy linux and it's powerful terminal even more in the future :D

Dave • Aug 23 '20

rm doesn't let you delete root anymore.

They fixed that, check the manpage.

Raphael Habereder • Aug 23 '20 • Edited

That doesn't mean that a cleaned out /etc/ or any other system-critical directory won't hurt you a lot. Sure, you can't "kill" a linux box with RM anymore, but you can still make it pretty damn unusable

Dave • Aug 23 '20

Isn't that what good permissions, not running as root by default, and backups, are all for?

Raphael Habereder • Aug 23 '20

Considering we are discussing this in a beginners post about Linux, the foundation of careful usage should still apply.

Other than that, yes you are certainly right. A beginner probably doesn't have these precautions in place though.

Comment hidden by post author - thread only accessible via permalink

Devang Hingu • Aug 22 '20

Wait a minute...!! i just saw title and thought.., it might be your story about linux. but it has totally different. 🤣🤣🤣🤣🤣. i think you title should be "basic linux command which developers user everyday."

Abhishek S. Sharma • Aug 22 '20

Yeah!! Agree, I can write that too; however, this my post I can write whatever I want. There are many commands in this post which I don't use on daily basis.
:c)

Christian Parpart • Aug 23 '20

Click bait. And I think he is right. But you are right, too. It will however not help you grow your views with that attitude. Think about it. ;-)

Omar • Aug 22 '20

I am also in love with terminal bro , It's really power to master it , even if it take some times. if every one here new and got scared try to move slowly from GUI to terminal (CLI) , maybe your not going to feel the power only after a time of learning terminal shortcuts.