[Bash] Create and Run Bash Scripts with Command Line Arguments

Create a script

See Chmod.md, how to create a sh file and modify premisson to exec mode.

Parameters

Paramters are referred by $1, $2....

For example:

echo "Hello $1"

Run:

./script.sh Wan

It print Hello Wan.

Example

Create a empty project

init-js.sh

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

Modify the chmod:

chmod u+x init-js.sh

Make a global accessable:

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

Now if you run init-js in other folder, it will create an empty js project for you and open the VSCode.

Function

greet() {
  return "$1 world"
}

greet "Hello" ## call greet function with "Hello" paramter

greeting = $(greet "Hello") ## Save the output of function calling into a variable

global and local variables

global = 123

test() {
  echo "global = $global"
  local local_var = "i am a local"
  echo "local_var = $local_var"
}

test

echo "global = $global"
echo "local_var = $local_var" ## you will not see this output correctly