BASH AUTOMATION
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+Table of Contents
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- 1. Automate daily development tasks with bash
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- 1.1. Lessons +
- 1.2. Navigate the file system + + +
- 1.3. View files and folders in bash + + +
- 1.4. Create and delete files and folders + + +
- 1.5. Move and Copy Files and Folders with bash + + +
- 1.6. Find Files and Folders with
findin bash
+ - 1.7. Search for text with
grep
+ - 1.8. Make HTTP requests in bash with
curl
+ - 1.9. Create and run bash scripts +
- 1.10. Store and Use Values with bash Variables +
- 1.11. Understand and use functions in bash +
- 1.12. Understand exit statuses in bash +
- 1.13. Use Conditional Statements in bash +
- 1.14. Chain Commands with Pipes and Redirect Output in bash +
+ - 2. Additional learning resources +
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+1. Automate daily development tasks with bash
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++This is the GitHub repo to accompany the Egghead Course "Automate daily development tasks with bash". Watch it on egghead.io +
+ ++This repository is structured more as a "cheatsheet" rather than having any runnable code. Click the lesson links to see the code that's covered in each lesson. +
+ ++— +
+ +
+Whether it’s for npm install or some git commands, most front-end devs have used bash sometime. Bash has been around awhile (first released in 1989) and it’s proven to be very efficient at automating tasks. Plus, bash is available on every commonly used operating system—it comes with macOS, is the default shell for many Linux distros, and is available on Windows via an emulator or the new Linux subsystem. In this course, we’ll learn the essentials of what every front-end developer should know about bash. The topics we cover will give you confidence in doing things like creating build scripts that run on continuous integration servers or quickly testing and debugging an API with curl. We’ll go over:
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- Interacting with the file system +
- Creating, moving, copying, and deleting files and folders +
- Finding files and text patterns in files +
- Creating and running scripts +
- Language syntax like variables and conditionals +
+Click on a lesson below to jump to the code samples for that lesson. +
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+1.1. Lessons
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- Navigate the filesystem in bash +
- View files and folders in bash +
- Create and Delete Files and Folders in bash +
- Move and Copy Files and Folders with bash +
- Find Files and Folders with find in bash +
- Search for text with grep +
- Make HTTP requests in bash with curl +
- Create and run bash scripts +
- Store and Use Values with bash Variables +
- Understand and use functions in bash +
- Understand exit statuses in bash +
- Use Conditional Statements in bash +
- Chain Commands with Pipes and Redirect Output in bash +
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+1.2. Navigate the file system
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+1.2.1. Change bash's current working directory
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+cd <file path here> +# to go up a directory from your current directory +cd .. ++
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+1.2.2. List a directory's contents
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+ls +# for more details, add -l (long) +ls -l +# this will output something like this: +# -rw-r--r-- 1 cameronnokes staff 1237 Jun 2 22:46 index.js +# in order, those columns are: +# permissions for you, your group, all +# number of links (hardlinks & softlinks) +# owner user +# owner group +# file size +# last modified time +# file name + +# to see hidden files/folders (like .git or .npmignore) +ls -a +# Note, flags can be combined like so +ls -la ++
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+1.3. View files and folders in bash
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+1.3.1. Output a file to the screen (stdout)
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+cat <file name> +# shows it with line numbers +cat -n <file name> ++
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+1.3.2. View a file in bash
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+# view the file without dumping it all onto your screen +less <file name> +# Some useful shortcuts in less +# Shift+g (jump to end) +# g (go back to top) +# / (search) +# q (quit/close) ++
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+1.3.3. View file/folder in default application associated with it
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+open <file/folder name> +# view current directory in Finder +open . +# specify an application to use +open <file name> -a TextEdit ++
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+1.4. Create and delete files and folders
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+1.4.1. Create a file
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+touch <file name> ++
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+1.4.2. Set or append to a file
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+# set the file's contents +echo 'hi' > file.txt +# append to file's contents +echo 'hi' >> file.txt +# note that if you pass a file name that doesn't exist, it'll get created on the fly ++
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+1.4.3. Create a directory
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+mkdir <folder name> +# make intermediary directories as needed +mkdir -p parent/child/grandchild ++
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+1.4.4. Remove a file
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+# Note, this permanently deletes a file +rm <file name> +# Remove a folder and it's contents, recursively +rm -rf <folder name> ++
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+1.5. Move and Copy Files and Folders with bash
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+1.5.1. Move a file
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+mv <target> <destination> +# for example, to rename a file +mv a.js b.js +# move all files in a folder to another folder +mv lib/* src ++
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+1.5.2. Copy a file
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+cp <target> <destination> +# copy everything recursively from one folder to another +cp -R src/* lib ++
+1.6. Find Files and Folders with
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+1.6. Find Files and Folders with find in bash
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+# find all the PNGs in a folder +find <path> -name "*.png" +# find all the JPGs (case insensitive) in a folder +find <path> -iname "*.jpg" +# find only directories +find <path> -type d +# delete all matching files +find <path> -name "*.built.js" -delete +# execute an arbitrary action on each match +# remember ~{}~ will be replaced with the file name +find <path> -name "*.png" -exec pngquant {} \; ++
+1.7. Search for text with
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+1.7. Search for text with grep
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+# Basic usage +grep <pattern> <target file or glob> +# Useful flags +# --color (colorizes matches) +# -n (show line numbers) +# -C <number> (show N lines above/below match for context) +# -e (regex search) ++
+1.8. Make HTTP requests in bash with
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+1.8. Make HTTP requests in bash with curl
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+The test server is available in the curl-practice-server directory. Run npm install && npm start to run it.
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+curl <url> +# Useful flags +# -i (show response headers only) +# -L (follow redirects) +# -H (header flag) +# -X (set HTTP method) +# -d (request body) +# -o (output to a file) + +# to POST JSON +# (technically you don't need -X POST because -d will make it POST automatically, but I like to be explicit) +curl -X POST -H "Content-Type: application/json" -d '{ "title": "Curling" }' http://localhost:3000/api/posts + +# POST a url encoded form +curl -X POST --data-urlencode title="Curling again" http://localhost:3000/api/posts + +# multiline curl (applies to any bash command) +curl -i -X PUT \ +-d '{ "title": "Changed title" }' \ +-H "Content-Type: application/json" \ +http://localhost:3000/api/posts + +# pretty print JSON with jsome +curl https://swapi.co/api/people/1/ | jsome ++
+Here's the jsome package that pretty prints JSON +
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+1.9. Create and run bash scripts
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+echo 'echo Hello World' > script.sh +chmod u+x script.sh +./script.sh ++
+The init-js.sh script for scaffolding a JS project
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+echo "Initializing JS project at $(pwd)" +git init +npm init -y # create package.json with all the defaults +mkdir src +touch index.js +code . ++
+One way to add that script to your $PATH:
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+cp init-js.sh /usr/local/bin/init-js ++
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+1.10. Store and Use Values with bash Variables
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+# no spaces between name, =, and value +var=123 +echo $var +# to make it accessible to all child processes of current shell, export it +export var +# this deletes the variable +unset var ++
+To see all environment variables +
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+env ++
+clone-to-temp.sh script:
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+temp=$(mktemp -d) +git clone --branch $1 $PWD $temp +echo "branch $1 cloned to $temp" +# run some tasks, tests, etc here ++
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+1.11. Understand and use functions in bash
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+greet() { + echo "$1 world" +} + +greeting=$(greet "howdy") + +echo "the greeting is $greeting" ++
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+global=123 + +test() { + echo "global = $global" + local local_var="i'm a local" + echo "local_var = $local_var" +} + +test + +echo "global = $global" +echo "local_var = $local_var" # will be empty because it's out of scope ++
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+1.12. Understand exit statuses in bash
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++Get the last run command's exit status +
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+ls +# will be 0 if it ran successfully, 1 - 255 for an error +echo $? ++
+Exit statuses and functions. script.sh
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+ok() { + return 0 +} + +fail() { + return 1 +} + +fail +ok ++
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+./script.sh +echo $? # exit status is same as the last run function/command ++
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+1.13. Use Conditional Statements in bash
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++Basic form +
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+# Some conditional primaries that can be used in the if expression: +# =, != string (in)equality +# -eq, -ne numeric (in)equality +# -lt, -gt less/greater than +# -z check variable is not set +# -e check file/folder exists + +if [[ $USER = 'cameronnokes' ]]; then + echo "true" +else + echo "false" +fi ++
+Conditionals can be used inline in a more ternary-like format +
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+[[ $USER = 'cameronnokes' ]] && echo "yes" || echo "no" ++
+check-status.sh for checking a URL is responding with a 200
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+check_status() { + local status=$(curl -ILs $1 | head -n 1 | cut -d ' ' -f 2) + if [[ $status -lt 200 ]] || [[ $status -gt 299 ]]; then + echo "$1 failed with a $status" + return 1 + else + echo "$1 succeeded with a $status" + fi +} + +check_status https://example.org +check_status https://example.org/404 ++
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+1.14. Chain Commands with Pipes and Redirect Output in bash
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++Pipes +
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+# ps ax will list all running processes +ps ax | grep Chrome | less +# get the file size after uglify + gzip +uglifyjs -c -m -- index.js | gzip -9 | wc -c ++
+Redirection +
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+# redirect stdout to a file +ls > ls.txt +# append stdout to a file +echo "hi" >> ls.txt ++
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+2. Additional learning resources
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- You can view a command's documentation right in bash with
man <command name>.
+ - Official bash manual +
- TLDP bash programming intro, basic +
- TLDP bash programming intro, advanced +