class: center, middle, inverse # Linux and Bash --- # Bash is in the top 10 most popular programming languages https://survey.stackoverflow.co/2024/technology#1-programming-scripting-and-markup-languages  --- # Installation **Windows**: Download Git Bash (https://git-scm.com/download/win) **Mac**: use the Terminal app **Linux**: Open a terminal We will be using the terminal to run bash commands, make sure you have it installed. --- # Shells and Terminals A shell is a command interpreter. It takes commands from the user, and delivers them to the operating system to perform. A terminal is a program that lets you interact with the shell. - Available on any OS - Flexible & Efficient - Great for prototyping and automating simple tasks --- # Bash (1989) Bourne Again Shell Bash is an enhanced version of the Bourne Shell, or sh (1977) Default shell on most UNIX operating systems --- # Bash interactive and non-interactive mode Interactive: allows running commands through a prompt, one command at a time. Non-interactive: run bash commands through scripts, automating certain logic. A script is a list of commands (same as the ones that can be typed in a command line), stored in a file. It executes commands sequentially. --- # Interactive mode: Commands BASH reads commands from its input (either a terminal or a file) Each "line" is treated as a command: an instruction to be carried out Bash divides each line into words separated by a whitespace character (space or tab) The first word of the line is the name of the command to be executed, all other words are arguments. `$ man man` `$` Usually indicates that the shell is Bash compatible For Mac and Linux: `man` "manual", displays manual documentation pages For Windows: `help` displays manual documentation pages https://tldr.inbrowser.app Each command on your system is likely to have a manual page In a UNIX OS, to leave the manual page use q and press enter --- # Navigating directories - mkdir - Creates a directory - `mkdir facultad` creates a directory called `facultad` - `mkdir facultad/programacion1` creates a directory called `programacion` inside `facultad/programacion1` - cd - Change directory - `cd facultad/programacion1` changes the current directory to `facultad` - touch - Create a file - `touch resumen_de_la_mejor_materia.txt` creates a file called `resumen_de_la_mejor_materia.txt` - ls - List directory's contents - `ls` lists the files in the working directory - `ls -F -R` lists the files in the directory and all subdirectories with their types - grep - Searches for a pattern - `ls | grep *.txt` # Searches for any file that ends with .txt --- # Piping - '|' allows connecting UNIX programs to each other. - `ls | grep hi` - ls lists the files in the working directory, this output is checked by the grep command for the word `hi` --- # Manipulating Files - cat - Read file and write it to the standard output - `cat resumen_de_la_mejor_materia.txt` prints the contents of the file `resumen_de_la_mejor_materia.txt` - cp - Copy File(s) - `cp resumen_de_la_mejor_materia.txt resumen_de_la_mejor_materia_2.txt` copies the file `resumen_de_la_mejor_materia.txt` to `resumen_de_la_mejor_materia_2.txt` - mv - Move File(s) - `mv resumen_de_la_mejor_materia_2.txt facultad/programacion1.txt` moves the file `resumen_de_la_mejor_materia_2.txt` to `facultad/programacion1.txt` - rm - Remove File(s) and directories - `rm facultad/programacion1.txt` removes the file `facultad/programacion1.txt` --- # Non-interactive mode The extention .sh is used for files that contain shell commands - `nano my_commands.sh` creates a file called my_commands and opens an editor - `bash my_commands.sh` executes the commands in the file in order --- # Other commands - echo - Writes arguments to the standard output - `echo rm *.txt` prints all the options to be removed to make sure we are deleteing what we want to delete. - pwd - Writes the absolute pathname of the current working directory - curl - Downloads files from the internet - `curl https://sebiglesias.com.ar/bash-test` # downloads the file `bash-test` from the internet - history - Shows the history of commands --- # Finding files and writing files - find - Searches for files in a directory hierarchy - `find . -name "*.txt"` searches for all files that end with .txt in the current directory - nano - Creates a file and opens it in a text editor - `nano resumen_de_la_mejor_materia.txt`# creates a file called `resumen_de_la_mejor_materia.txt` and opens it in a text editor - diff - Compares files line by line - `diff resumen_de_la_mejor_materia.txt resumen_prog1.txt` # compares the files `resumen_de_la_mejor_materia.txt` and `resumen_prog1.txt` --- # Environment variables - Environment variables are special variables that contain information about your login session. They're stored for the system shell to use when executing commands. They exist whether you're using Linux, Mac, or Windows. Many of these variables are set by default during installation or user creation - `echo $HOME` # prints the value of the environment variable `HOME` - `HELLO="Hello World"` # creates an environment variable called `HELLO` with the value `Hello World` - `echo $HELLO` # prints the value of the environment variable `HELLO` --- # Aliases - Aliases are a way to create shortcuts for commands. They are useful for commands that you use frequently, or commands that are long and difficult to type. - `alias ll='ls -l'` # creates an alias called `ll` for the command `ls -l` - `ll` # lists all the files in the working directory - `unalias ll` # removes the alias `ll` - `alias` # lists all the aliases --- # Hands on - **Bashcrawl**: https://gitlab.com/slackermedia/bashcrawl - Bashcrawl is a game that teaches you how to use the command line. - Follow the instructions to download it and run it. - [**Practice from class**](https://docs.google.com/document/d/1U42SZKWenmtOXu2_zX8Fz5wAjYJ0eRJJDxNHVQNEjPo/edit?usp=sharing)