bash script template

#!/bin/bash

echo hello world

Here is what the above code is Doing:
1. The first line is a shebang. It tells the computer that this file is a bash script.
2. The second line is a comment. It’s ignored by the computer.
3. The third line is a command. It prints the text “hello world” to the screen.

Now, let’s run the script.

“`
$ ./hello.sh
hello world
“`

## Variables

Variables are a way to store information.

“`
$ name=”John”
$ echo $name
John
“`

## Functions

Functions are a way to group commands.

“`
$ function hello {
> echo “hello world”
> }
$ hello
hello world
“`

## Conditionals

Conditionals are a way to make decisions.

“`
$ name=”John”
$ if [ $name = “John” ]; then
> echo “Hello John”
> else
> echo “Hello stranger”
> fi
Hello John
“`

## Loops

Loops are a way to repeat commands.

“`
$ for i in 1 2 3 4 5; do
> echo $i
> done
1
2
3
4
5
“`

## Arrays

Arrays are a way to store multiple values.

“`
$ names=(“John” “Paul” “George” “Ringo”)
$ echo ${names[0]}
John
“`

## Hashes

Hashes are a way to store key-value pairs.

“`
$ declare -A names
$ names=([first]=”John” [last]=”Lennon”)
$ echo ${names[first]}
John
“`

## Input

Input is a way to get data from the user.

“`
$ read -p “What is your name? ” name
What is your name? John
$ echo “Hello $name”
Hello John
“`

## Exit Status

Exit status is a way to communicate the success of a command.

“`
$ ls does-not-exist.txt
ls: cannot access ‘does-not-exist.txt’: No such file or directory
$ echo $?
1
“`

## Standard Input

Standard input is a way to send data to a command.

“`
$ echo “John” | wc -c
4
“`

## Standard Output

Standard output is a way to get data from a command.

“`
$ echo “John”
John
“`

## Standard Error

Standard error is a way to get error messages from a command.

“`
$ ls does-not-exist.txt
ls: cannot access ‘does-not-exist.txt’: No such file or directory
“`

## Redirection

Redirection is a way to send output to a file.

“`
$ echo “John” > name.txt
$ cat name.txt
John
“`

## Pipes

Pipes are a way to send the output of one command to another command.

“`
$ echo “John” | wc -c
4
“`

## Background Jobs

Background jobs are a way to run a command without waiting for it to finish.

“`
$ sleep 10 &
[1] 1234
$ jobs
[1]+ Running sleep 10 &
“`

## Signals

Signals are a way to send a