# Today's Goal To understand how executable scripts work using the `$PATH` variable and explore some options for creating your own. --- # Agenda: 1. [Review](#redirect) 2. [Understanding the Environment](#environment) 3. [Workshop](#workshop) --- name: review # Redirect Operators - Overwrite Operator - Append Operator - Input Operator - Pipe Operator --- count: false # Redirect Operators - Overwrite Operator: .eight[>] - Append Operator: .eight[>].eight[>] - Input Operator: .eight[<] - Pipe Operator: .eight[|] --- # Commands That Use Redirects - .eight[wc] - .eight[sort] - .eight[uniq] - .eight[grep] - .eight[sed] --- # Editing Our Settings - Which text editors have we seen so far? - What two files configure BASH? - Which command reloads our settings? - Which command creates a variable? --- count: false # Editing Our Settings - Which text editors have we seen so far? .eight[nano, vim, TextEdit] - What two files configure BASH? .eight[.bashrc, .bash_profile] - Which command reloads our settings? .eight[source] - Which command creates a variable? .eight[export] --- # Common Environment Variables - .eight[$USER] - .eight[$HOME] - .eight[$PS1] - .eight[$PATH] Use .eight[echo $VARIABLE] to print the values for each variable. --- name: environment class: middle, center # So what is the Environment? --- # The environment is the context that your programs are running in. --- class: middle, center <div style="padding: 1rem; margin: 1rem; border: 2px solid #000;"> Computer <div style="padding: 1rem; margin: 1rem; border: 2px solid #000;"> BASH </div> </div> --- class: middle, center <div style="padding: 1rem; margin: 1rem; border: 2px solid #000;"> Computer <div style="padding: 1rem; margin: 1rem; border: 2px solid #000;"> BASH <div style="padding: 1rem; margin: 1rem; border: 2px solid #000;"> nano </div> </div> </div> --- # Where did this command come from? - BASH looks through each directory in the $PATH - When it finds the program, then it can run it ```sh $ which nano /usr/bin/nano ``` --- # Let's look at the PATH ```sh $ echo $PATH ``` .fourteen[Is /usr/bin/ in the list of directories?] --- # What else is in there? ```sh $ ls /usr/bin/ ``` .fourteen[Recognize anything?] --- class: middle, center # .eleven[Time to get dangerous!] We're going to break our $PATH --- # Step 1: Make a new script ```sh $ mkdir ~/scripts $ cd ~/scripts $ touch rm $ ls -l total 0 -rw-r--r-- 1 zach staff 0 Aug 27 12:45 rm ``` --- # Step 2: Make it executable ```sh $ chmod +x rm $ ls -l total 0 -rwxr-xr-x 1 zach staff 0 Aug 27 12:45 rm ``` --- # Step 3: Add lines to the script ```sh $ nano rm ``` And add these lines to it: ```sh #!/bin/bash echo "Hello World" ``` --- # Step 3b: Test the script ```sh $ ./rm Hello World ``` --- # Step 4: Add a directory to the $PATH ```sh $ nano ~/.bash_profile ``` At the bottom, add this line: ```sh export PATH="$HOME/scripts:$PATH" ``` --- # Step 4b: Update your settings ```sh $ source ~/.bash_profile ``` --- # Now try to delete your new script ```sh $ rm rm Hello World ``` --- name: workshop class: middle, center # Workshop ## .eight[Your chance to explore something new or practice what we've learned.] --- # Workshop - [Learn Enough Command Line to Be Dangerous](https://www.learnenough.com/command-line-tutorial) - [101 Bash Commands and Tips for Beginners to Experts](https://dev.to/awwsmm/101-bash-commands-and-tips-for-beginners-to-experts-30je) - [CLI Challenges](https://cmdchallenge.com/) - [Codecademy: Learn Bash Scripting](https://www.codecademy.com/courses/learn-the-command-line/lessons/learn-bash-scripting/exercises/introduction) - [TLDP: Bash Programming Intro](http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html) --- class: middle, center # The End!