Array in shell programming

程序设计

Array: An array is a numbered list of strings: it maps integers to strings.

Creating arrays

With =() syntax.

names=("John" "$USER")

Glob can also be used.

files=(~/*'.jpg')

To list files

Do not use

l=$(ls)
l=($(ls))

Use

l=(*)

Get element number

echo ${#array[@]}

Expanding elements

We can use a for loop to iterate over the elements

for i in "${l[@]}"; do
    echo "$i"
done

We use the quoted form again here: "${l[@]}". Bash replaces this syntax with each element in the array properly quoted.

Use "${!l[@]}" to loop over the indices of arrays.

for i in "${!l[@]}"; do
    echo "${l[i]}"
done

Since it works with sparse array, it better than ${#l[@]}.