Comment environmental variables

export SETUPTOOLS_ENABLE_FEATURES=legacy-editable

See distro / linux OS

lscpu

cat /etc/*-release

See architecture

Log into root

$ sudo -s

Upload public key

$ ssh-keygen

$ vi ~/.ssh/authorized_keys

upload id_rsa.pub

SSH

$ ssh user@IP

See ports in use

lsof -i -P -n | grep LISTEN

Kill process on port

kill $(lsof -t -i:8055)

passwords

openssl

 simple password encrypt (example abc)

echo abc | openssl aes-256-cbc -a -salt -pass pass:somepassword -pbkdf2

echo U2FsdGVkX1+W+KyjQ/FywzWm2EXFDe1GnT1MXweYuoU= | openssl aes-256-cbc -d -a -pass pass:somepassword -pbkdf2

mkpasswd

 simple password encrypt (example abc)

echo abc | mkpasswd -m sha-512

Install packages

$ sudo apt install vim --yes

$ apt-get install vim -y 

Uninstall packages

Update packages

$ sudo apt-get update

$ sudo apt-get upgrade

See environmental variables

$ env

$ printenv

Create an environmental variable

export BLOB2_KEY=aaa

 Clear an environmental variable

unset BLOB2_KEY

See CPUS

$ nprocs

$ lscpu

See RAM / memory

$ free -mh

See disk space

$ df -h

See IP address

curl -s https://checkip.amazonaws.com

See size of directory

du -sh file.zarr

Delete large number of files

for f in *.zarr; do rm -rf "$f"; done

Open a terminal

CTRL + ALT + t

Unzip  tar.gz file

tar -xvf archive.tar.gz

 gzip a file

gzip -c original_file > compressed_copy.gz

Put stuff from a folder to a zip file

tar -czf FOLDER.tar.gz FOLDER

Create a csv file

echo "a" > file.csv && echo "1" >> file.csv

Date

date +"%Y-%m-%dT%H:%M:%S"

date +"%Y-%m-%dT%H:%M:%S%z"

Change windows

CTRL + ALT + DOWN

See jobs

ps -ef

Kill all jobs

pkill -u USERNAME

Search for a file

...

Detect second screen

https://askubuntu.com/questions/1033785/external-monitor-not-detected-on-ubuntu-18-04 

https://linuxconfig.org/how-to-install-the-nvidia-drivers-on-ubuntu-18-04-bionic-beaver-linux 

$ ubuntu-drivers devices

$ sudo ubuntu-drivers autoinstall

https://www.nvidia.com/en-us/geforce/drivers/

sudo apt-get purge 'nvidia*'

sudo add-apt-repository ppa:graphics-drivers

sudo apt-get update

sudo ubuntu-drivers autoinstall

Bash

 example.sh:

#!/usr/bin/bash

year=2018

echo ${year}

delete folders in a folder in a loop

for f in *; do rm -rf $f; done

Size of folder

For loop

for year in {2003..2018}; do

month_list=(01 02 03 04 05 06 07 08 09 10 11 12)

periods_list=(31 29 31 30 31 30 31 31 30 31 30 31)

i=0

for month in ${month_list[@]}; do

   periods=${periods_list[$i]}

   i=$(expr $i + 1)

done

 simple password encrypt (example abc)

echo abc | openssl aes-256-cbc -a -salt -pass pass:somepassword -pbkdf2

echo U2FsdGVkX1+W+KyjQ/FywzWm2EXFDe1GnT1MXweYuoU= | openssl aes-256-cbc -d -a -pass pass:somepassword -pbkdf2

at

at now +1 minute

echo hello

Ctrl-D

echo echo hello world | at now

echo "command_to_be_run" | at now +1 minute

at 09:00 <<EOF

command_to_be_run

EOF

at -l | awk '{printf "%s ", $1}' | xargs atrm

Create animation

convert -delay 50 -loop 1 *.png animation.gif

Find

Replace a with b in file.txt

find file.txt -type f -exec sed -i "" "s/a/b/g" {} \;

 Replace , "a"] with ] in file txt

find file.txt -type f -exec sed -i "" 's/, "a"]/]/g' {} \;