How to get the last character of a string in a she

Question

I have written the following lines to get the last character of a string:

str=$1
i=$((${#str}-1))
echo ${str:$i:1}

It works for abcd/:

$ bash last_ch.sh abcd/
/

It does not work for abcd*:

$ bash last_ch.sh abcd*
array.sh assign.sh date.sh dict.sh full_path.sh last_ch.sh

It lists the files in the current folder.

Answer 1

Try:

"${str:$((${#str}-1)):1}"

For e.g.:

someone@mypc:~$ str="A random string*"; echo "$str"
A random string*
someone@mypc:~$ echo "${str:$((${#str}-1)):1}"
*
someone@mypc:~$ echo "${str:$((${#str}-2)):1}"
g

Answer 2

That's one of the reasons why you need to quote your variables:

echo "${str:$i:1}"

Otherwise, bash expands the variable and in this case does globbing before printing out. It is also better to quote the parameter to the script (in case you have a matching filename):

sh lash_ch.sh 'abcde*'

Also see the order of expansions in the bash reference manual. Variables are expanded before the filename expansion.

To get the last character you should just use -1 as the index since the negative indices count from the end of the string:

echo "${str: -1}"

NOTE: The space after the colon (:) is required!

This approach will not work without the space.