linux.softwareshinobi.com/landing/docs/Bash-Scripts/008-bash-arrays.md

# Arrays

Arrays are essential. They let a single variable hold multiple values. Initialize them by listing values, separated by spaces, inside parentheses:

```bash
# Example initialization:
my_array=("value 1" "value 2" "value 3" "value 4")
```

Access array elements using their numeric index. **Always use curly brackets.**

Let's create `arrays.sh` to demonstrate:

```bash
touch arrays.sh
```

Now, open `arrays.sh` and add:

```bash
#!/usr/bin/env bash

my_array=("value 1" "value 2" "value 3" "value 4")

echo "Second element (index 1): ${my_array[1]}"
echo "Last element (index -1): ${my_array[-1]}"
echo "All elements: ${my_array[@]}"
echo "Total elements: ${#my_array[@]}"
```

Save and exit. Make it executable:

```bash
chmod +x arrays.sh
```

Run your script:

```bash
./arrays.sh
```

Output:

```
value 2
value 4
value 1 value 2 value 3 value 4
4
```

### Slicing

Extract specific portions of an array or string using slicing notation.

Create `slicing.sh`:

```bash
touch slicing.sh
```

Open `slicing.sh` and add these examples:

```bash
#!/usr/bin/env bash

letters=("A" "B" "C" "D" "E")

echo "Original array: ${letters[@]}"

echo "Example 1 (start 0, length 2): ${letters:0:2}" # Prints AB
echo "Example 2 (start 0, all elements): ${letters::5}" # Prints ABCDE
echo "Example 3 (start 3, to end): ${letters:3}" # Prints DE
```

Save and exit. Make it executable:

```bash
chmod +x slicing.sh
```

Run `slicing.sh`:

```bash
./slicing.sh
```

Output:

```
A B C D E
AB
ABCDE
DE
```

Mastering arrays and slicing gives you precise control over your data structures.