cd <file path here>
# to go up a directory from your current directory
cd ..

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

cat <file name>
# shows it with line numbers
cat -n <file name>

# 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)

open <file/folder name>
# view current directory in Finder
open .
# specify an application to use
open -a TextEdit <file name>

touch <file name>

# 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

mkdir <folder name>
# make intermediary directories as needed
mkdir -p parent/child/grandchild

# Note, this permanently deletes a file
rm <file name>
# Remove a folder and it's contents, recursively
rm -rf <folder name>

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

cp <target> <destination>
# copy everything recursively from one folder to another
cp -R src/* lib

# 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 {} \;

# 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)

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

echo 'echo Hello World' > script.sh
chmod u+x script.sh
./script.sh

echo "Initializing JS project at $(pwd)"
git init
npm init -y # create package.json with all the defaults
mkdir src
touch index.js
code .

cp init-js.sh /usr/local/bin/init-js

# 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

env

temp=(mktemp -d)
git clone --branch $1 $PWD $temp
echo "branch $1 cloned to $temp"
# run some tasks, tests, etc here

greet() {
  echo "$1 world"
}

greeting=$(greet "howdy")

echo "the greeting is $greeting"

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

ls
# will be 0 if it ran successfully, 1 - 255 for an error
echo $?

ok() {
  return 0
}

fail() {
  return 1
}

fail
ok

./script.sh
echo $? # exit status is same as the last run function/command

# 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

[[ $USER = 'cameronnokes' ]] && echo "yes" || echo "no"

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

# 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

# redirect stdout to a file
ls > ls.txt
# append stdout to a file
echo "hi" >> ls.txt