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

问题:

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.

回答1:

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.

回答2:

Per @perreal, quoting variables is important, but because I read this post like 5 times before finding a simpler approach to the question at hand in the comments...

str='abcd/'
echo "${str: -1}"

Output: /

str='abcd*'
echo "${str: -1}"

Output: *

Thanks to everyone who participated in this above; I've appropriately added +1's throughout the thread!

回答3:

I know this is a very old thread, but no one mentioned which to me is the cleanest answer:

echo -n $str | tail -c 1

Note the -n is just so the echo doesn't include a newline at the end.

回答4:

Single line:

${str:${#str}-1:1}

Now:

echo "${str:${#str}-1:1}"

回答5:

Every answer so far implies the word "shell" in the question equates to Bash.

This is how one could do that in a standard Bourne shell:

printf $str | tail -c 1

回答6:

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

回答7:

another solution using awk script:

last 1 char:

echo $str | awk '{print substr($0,length,1)}'

last 5 chars:

echo $str | awk '{print substr($0,length-5,5)}'

回答8:

echo $str | cut -c $((${#str}))

is a good approach