Everything you need to know about Bash array operations

Starting with a simple text file:

$ cat list.txt
fork
knife
spoon

And build an array out of that:

$ myarray=($(cat list.txt))

We can get the number of elements in our bash array with

$ echo ${#myarray[@]}
3

You can print the whole array with

$ echo ${myarray[@]}
fork knife spoon

Or you can use a for loop to walk the bash array and print each element:

$ for i in  ${myarray[@]}; do echo $i; done
fork
knife
spoon

You can also do a for loop but use array indexes instead of each element:

$ for i in  ${!myarray[@]}; do echo $i; done
0
1
2

Putting it together:

$ for i in  ${!myarray[@]}; do echo "$i -> ${myarray[i]}"; done
0 -> fork
1 -> knife
2 -> spoon

We can remove an array element with:

$ for i in  ${!myarray[@]}; do if [ "${myarray[i]}" = "knife" ]; then unset myarray[i]; fi; done

Which leaves us with:

$ for i in  ${!myarray[@]}; do echo "$i -> ${myarray[i]}"; done
0 -> fork
2 -> spoon

Unfortunately, there are no two or three dimensional arrays in bash. But you can usually get away with parsing the contents of a regular, one dimension array.