Rock & roll with shell

In this session, we will get familiar with shell commands with pop and rock music!

Getting started

• Clone this repo git clone https://github.com/thoughtworks-jumpstart/learn-shell.git
• get into the project directory (cd): cd learn-shell
• Complete the tasks below sequentially

Tasks

Navigate around your project

• Find out the absolute path to where you currently are pwd
• List the contents of your current directory ls
• List the contents of your current directory with some options: ls -l and ls -la
• Navigate to the pop directory: cd pop
• Navigate back to the parent directory cd ..
• Navigate to the adele directory: cd pop/adele
• Navigate back: cd ../..

Read files

• Print the lyrics to adele's "hello.txt" cat ./pop/adele/hello.txt or cat pop/adele/hello.txt (the . is optional)
• Print the lyrics to adele's "someone-like-you.txt" cat pop/adele/someone-like-you.txt
• Replace cat with less (press q when you want to exit)

Rename files and directories

• Renaming files/directories
  • mv ./pop/adele/SET-FIRE-TO-THE-RAIN.txt ./pop/adele/set-fire-to-the-rain.txt
  • mv pop old-pop

Move files and directories

• Move set-fire-to-the-rain.txt to the correct folder (pop/adele) mv my_source_filepath my_target_filepath
  • Move a file: mv ./set-fire-to-the-rain.txt ./pop/adele/
  • Move and rename simultaneously: mv ./set-fire-to-the-rain.txt ./pop/adele/SET-FIRE-TO-THE-RAIN.txt

Create files and directories

• Create files touch touch my-first-file.txt
• Create directories mkdir jazz

Delete files and directories

• Delete files rm somefile or rm file.txt another-file.js
• Delete directories rm -rf jazz

See history

• Type history to see a history of commands you have typed

Pipe

Pipe (|) allows us to pipe the output of one command as the input to another command

• Example use case #1: grep

  • history | grep 'touch'
  • history | grep '.txt'

• Example use case #2: wc (count)

  • count number of lines in a file
    • cat ./pop/adele/hello.txt | wc -l
    • cat ./pop/adele/someone-like-you.txt | wc -l

RTFM - Read the friendly manual

• Read manuals with the man command. E.g. man mkdir, man ls

Navigate man pages

• man uses less as its default pager
• h to get help (this is the only one you have to remember)
• q to quit
• f to move forward (you can also use the SPACE key)
• b to move backward
• /pattern to search for something; use n for next search occurence and p to go back to the first occurence

PATH

PATH is an environment variable on Unix-like operating systems, DOS, OS/2, and Microsoft Windows, specifying a set of directories where executable programs are located. In general, each executing process or user session has its own PATH setting.

We can check what's in your PATH with echo $PATH

If you have scripts you want to run, you would have to cd into your directory and then run ./my-script.sh.

Alternatively, you can add a directory to your PATH which will allow you to execute my-script.sh. Let's see how to do this.

• Temporarily add folder scripts to your path to make it available to the terminal

  • export PATH=$PATH:<absolute_path_to_folder>
  • Example would be export PATH=$PATH:/Users/sgyaminmhd/jumpstart/learn-shell/scripts
  • echo $PATH to check that it's added to the end of the $PATH
  • Return to your home directory using ~ and run hello_world.sh
  • It will run the executable script!
  • Close your terminal session and run echo $PATH to notice that your $PATH is back to normal

• Permanently add the directory to your PATH by adding it in your .zshrc file

  • export PATH=$PATH:<absolute_path_to_folder> at the top of the file
  • save your file
  • Open a new terminal session (important). Close any old session and open a new one for the new PATH to take effect
  • Return to your home directory using ~ and run hello_world.sh
  • It will run the script!
  • Close your terminal and run echo $PATH to notice the new addition is persisted to the PATH