Arrays
Arrays is another hidden gem in BASH. BASH uses normal paranthesis to denote the start and end of arrays and a space signals the start of the next item:
fruit_array=("apples" "oranges" "bananas" "peaches" "papayas")
Iterating an array using indexes
Iterating using an index isn't that much different from C style languages. The unusual bit, is the double parenthesises and the extravagant reading of the array length:
for (( i = 0; i < ${#fruit_array[@]}; i++ )); do
echo $i "=" ${fruit_array[$i]}
done
Iterating an array without an index
If you don't need the index variable, you can also just iterate through the array values like this:
for fruit in ${fruit_array[@]}; do
echo $fruit
done
Starting iterating on a specified index in the array
If you wish to address just a sub set of the array, you can add the indexes inside the curly braces. Here, I start iterating from the second item of the array:
for fruit in ${fruit_array[@]:1}; do
echo $fruit "(skipped the first one)"
done
Whereas here, I only want the the middle two fruits:
for fruit in ${fruit_array[@]:1:3}; do
echo $fruit "(skipped the first and last ones)"
done
Creating an array of files
Often, you find yourself wanting a set of files into an array.
This is easy,. simply do the following to get all
tar.gz files in an array:
tarballs=($(ls /my/dir/*.tar.gz))
