bash loop through all chars in string

Question

How should I loop through all chars in a string.

My pseudocode

stringVar="abcde"

for var in stringvar
{
   do some things with var
}

result i need
a

b

c

d

I want to loop all the vars but i can only get it to work with a whitespace splitted var like

 stringVar="a b c"


for var in stringVar; do
   echo $var
done;

result

a

b

c

but i cant do it for a string that isnt split with whitespaces.

The question is flagged as duplicate but not one of the answers (with upvotes) is available in the linked questions..

@alfasin they dont explain how to perform an action on each char. — Sven van den Boogaart, Apr 12 '15 at 19:13
[Yes they do](http://stackoverflow.com/a/10552175/635608), @SvenB — Mat, Apr 12 '15 at 19:14
read this answer more carefully. http://stackoverflow.com/questions/10551981/how-to-perform-a-for-loop-on-each-character-in-a-string-in-bash/10552078#10552078 — shellter, Apr 12 '15 at 19:17
@IgnacioVazquez-Abrams i try to loop trough a word and check for each var if it is in another word, if one is not i must return false else if all are in the other word return true; — Sven van den Boogaart, Apr 12 '15 at 19:30
Then why wouldn't you just ask about that in the first place? — Ignacio Vazquez-Abrams, Apr 12 '15 at 19:32
@IgnacioVazquez-Abrams I tought it would be to specific and i could do it myself if i could loop all the vars, — Sven van den Boogaart, Apr 12 '15 at 19:33
@Mat the solutions are also different, i think the solutions on my question are better. — Sven van den Boogaart, Apr 12 '15 at 19:44
@IgnacioVazquez-Abrams ive posted another question thats more specific — Sven van den Boogaart, Apr 12 '15 at 20:03
@SvenB [What you believe...](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem) — muru, Apr 12 '15 at 20:50
New question: http://stackoverflow.com/questions/29594032/bash-shell-test-if-all-var-in-one-string-are-in-another-string — tripleee, Apr 13 '15 at 04:43

hek2mgl · Answer 1 · 2015-04-12T19:26:50.993

7

You can use read for that:

string="abcde"
while read -n 1 char ; do
    echo "$char"
done <<< "$string"

Using -n 1 read will read one character at a time. However, the input redirection <<< adds a newline to the end of $string.

edited Apr 12 '15 at 19:26

answered Apr 12 '15 at 19:16

hek2mgl

this method skips white spaces, unfortunately – almaceleste Dec 13 '20 at 15:01
can't reproduce – hek2mgl Dec 14 '20 at 09:33
you used `echo` which creates a new line on each iteration. if you try with `printf` you'll see that this method skips spaces. here is an [example](https://repl.it/@almaceleste/loop-chars#main.sh) – almaceleste Dec 14 '20 at 10:45
ok, you have to use `IFS= read -n 1 char` to read spaces too. example: [read-spaces](https://repl.it/@almaceleste/read-spaces#main.sh) – almaceleste Dec 14 '20 at 11:12
@almaceleste https://pastebin.com/BTZ7BNjB – hek2mgl Dec 14 '20 at 11:33
@hek2ml, your example does not work with spaces - it skips them. to test this behavior simply change `echo "@char"` to `printf "@char"` or use `echo` with some mark in the beginning and ending of the printed string, for example `'` (single quote) - like `echo "'$char'"`. [here](https://repl.it/@almaceleste/loop-chars-2#main.sh) is your code with single quotes appended to the `echo` command. if you want the command `read -n 1 char` to read spaces, you need to prepend it with `IFS=` or `IFS=""` or `IFS=''` like in this [example](https://repl.it/@almaceleste/loop-chars-3#main.sh) – almaceleste Dec 14 '20 at 14:31
1

Now I understand what you mean. – hek2mgl Dec 14 '20 at 14:40
ps: will review my answer later, at work atm.. thank you! – hek2mgl Dec 14 '20 at 15:59

score 3 · Answer 2 · answered Apr 12 '15 at 19:15

3

stringVar="abcde"
for ((i=1;i<=${#stringVar};i++)); do
  echo ${stringVar:$i-1:1}
done

Output:

a
b
c
d
e

answered Apr 12 '15 at 19:15

Cyrus

4

Why not `for ((i = 0; i < ${#stringVar}; i++)); do echo ${stringVar:$i:1}` ? – David C. Rankin Apr 12 '15 at 19:31
1

Yes, this is easier. – Cyrus Apr 12 '15 at 19:35

2 Answers2