Linux

# replace _file_name_ with the name of the file that is to be made executable including its filetype suffix, e.g. ".py"
chmod +x _file_name_

# print message
echo "Test!"

# create new directory
mkdir new_directory

# change directory
cd new_director

# print current working directory
pwd

# copy file
cp ../spider.txt .

# create empty file
touch myfile.txt

# list files and directories in current directory (with additional information using -l, including hidden files -a)
ls
ls -l
ls- la

# combine ls via a pipe to the less command to show only so many entries at a time
ls -l | less # you can quit with "q"

# rename a file
mv my.file.txt emptyfile.txt

# delete a file
rm *
  
# delete an empty directory
rmdir new_directory/
  
# list all running process on the computer
ps-ax
ps-ax | grep ping # filter process names through grep

# kill a process
kill 4619 # where 4619 is the process ID (PID)

#!/bin/bash

echo "Starting at: $(date)" # the dollar sign tells the program to execute this file inside of the string and then convert the output of it into a string
echo # print empty line

# add separating line
line="-----------------------------------"

echo "UPTIME"
uptime
echo $line

echo "FREE"
free
echo $line

echo "WHO"; echo; free # you can write commands on the same line separating them by semicolons

echo "Finishing at: $(date)"

#!/bin/bash

n=1 # in Bash, there are no spaces allowed when declaring variables
while [ $n -le 5]; do # the "[ condition ]"-syntax is equivalent to the "test" command
  echo "Iteration number $n"
  ((n+=1)) # in Bash, we use double parentheses to perform arithmetic operations on variables
done

#!bin/bash

for fruit in peach orange apple; do # we represent a list in Bash by simply listing valkues/variables with spaces in between
  	echo "I like $fruit!"
done

#!/bin/bash

for file in *.HTM; do
  name=$(basename "$file" .HTM) # surround the filename with double quotes to account for file names with spaces
  echo mv "$file" "$name.html" # put echo in front when testing to see what the program would do without actually changing anything yet
done

#!/bin/bash

for file in *.HTM; do
  name=$(basename "$file" .HTM) # surround the filename with double quotes to account for file names with spaces
  echo mv "$file" "$name.html" # put echo in front when testing to see what the program would do without actually changing anything yet
done

#!/bin/bash

for logfile in /var/log/*log; do
	echo "Processing: $logfile"
    # the following line splits the logfile entry line with an empty space as delimiter and then keeps only everything from field five onwards
    cut -d" " -f5- $logfile | sort | uniq -c | sort -nr | head -5
done

#!/bin/bash

>oldFiles.txt
files=$(grep " jane " ../data/list.txt | cut -d ' ' -f 3)
for file in $files; do
        if [ -e $HOME$file ]; then
        echo $HOME$file >> oldFiles.txt;
        fi
done

#!/usr/bin/env python3
import sys
import subprocess

with open(sys.argv[1]) as f:
        for line in f:
                old_name = line.strip()
                new_name = old_name.replace("jane","jdoe")
                subprocess.run(["mv",old_name,new_name])
        f.close()

# create diff file
diff old_file new_file > changes.diff
diff -u old_file new_file > changes.diff # with additional context

# apply diff file
patch file_to_patch < changes.diff

sudo puppet agent -v --test

# install docker
sudo apt-get install docker.io

# create and run a container from an image from the Docker Hub
sudo docker run --name firstContainer ubuntu:latest # where firstContainer is the name of the container

# list locally available docker containers
sudo docker ps -a

# open a docker container in interactive mode in the terminal
sudo docker run -it --name myContainer ubuntu:latest # where myContainer is the container name
# you can exit the container by pressing CTRL+P and CTRL+Q

# attach container to terminal
sudo docker attach myContainer # the container will now stay open in the background even after exiting via CTRL+P and CTRL+Q

# execute commands in the container running in the background
sudo docker exec myContainer echo $PATH

# delete containers
sudo docker rm -f firstContainer myContainer

# create new docker image based on your local environment/container
sudo docker commit myNginx docker_id/image_name # where myNginx is the name of your currently running container

# create new docker container from an image from a previously committed image
sudo docker run -it --name nginxNew docker_id/image_name

# list images on your machine
sudo docker image ls

# login to your docker hub account from the terminal
sudo docker login # you will be prompted to enter your id and password

# push an image to docker hub when logged into your docker account
sudo docker push docker_id/image_name

# run a docker container in the background
sudo docker run -d --name myApp nginx

# start an interactive bash terminal for the container running in the background
sudo docker exec -it myApp bashapt-get

# stop a running container
sudo docker stop myApp

# start a stopped container again
sudo docker start myApp

# start a web service using nginx
service nginx start

# check nginx landing page using curl
curl http://localhost:80

# check the status of the web server i.e apache2
sudo systemctl status apache2

# restart the service
sudo systemctl restart apache2

# return network-related information using a combination of flags along with the netstat command to check which process is using a particular port
sudo netstat -nlp

# find python3 programs running
ps -ax | grep python3

# kill a process by its process ID (PID)
sudo kill [process-id]

# let's check for the availability of any service with the keywords "python" or "jimmy"
sudo systemctl --type=service | grep jimmy

# stop and disable a service using
sudo systemctl stop _servicename_ && sudo systemctl disable _servicename_

tar xf ~/someData.tar.gz

crontab -e

sudo apt install stress
stress --cpu 8

readlink -f file.txt