Yrurtj

You may want to break on grapheme clusters instead of characters if the intent is to print text vertically. For instance with a e with an acute accent:

• 
  

  With grapheme clusters (e with its acute accent would be one grapheme cluster):

  
  
  

  $ perl -CLAS -le 'for (@ARGV) {print for /X/g}' $'Steu301phane'
  
  S
  
  t
  
  é
  
  p
  
  h
  
  a
  
  n
  
  e
  
  

  
  
  

  (or grep -Po 'X' with GNU grep built with PCRE support)

  
  


• 
  

  With characters (here with GNU grep):

  
  
  

  $ printf '%sn' $'Steu301phane' | grep -o .
  
  S
  
  t
  
  e
  
  
  
  p
  
  h
  
  a
  
  n
  
  e
  
  

  
  


• 
  

  fold is meant to break on characters, but GNU fold doesn't support multi-byte characters, so it breaks on bytes instead:

  
  
  

  $ printf '%sn' $'Steu301phane' | fold -w 1
  
  S
  
  t
  
  e
  
  �
  
  �
  
  p
  
  h
  
  a
  
  n
  
  e
  
  

  
  

On StackOver which only consists of ASCII characters (so one byte per character, one character per grapheme cluster), all three would give the same result.

If you have perl6 in your box:

$ perl6 -e 'for @*ARGS -> $w { .say for $w.comb }' 'cường'       

c

ư

ờ

n

g

work regardless of your locale.

With many awk versions

awk -F '' -v OFS='n' '{$1=$1};1' <<<'StackOver'

The below will be generic:

$ awk -F '' 

   'BEGIN { RS = ""; OFS = "n"} {for (i=1;i<=NF;i++) $i = $i; print }' <file_name>

echo StackOver | sed -e 's/./&n/g'

S

t

a

c

k

O

v

e

r

Since you specifically asked for an answer in bash, here's a way to do it in pure bash:

while read -rn1; do echo "$REPLY" ; done <<< "StackOver"

Note that this will catch the newline at the end of the "here document". If you want to avoid that, but still iterate over the characters with a bash loop, use printf to avoid the newline.

printf StackOver | while read -rn1; do echo "$REPLY" ; done

Also Python 2 can be used from the command line:

python <<< "for x in 'StackOver':

   print x"

or:

echo "for x in 'StackOver':

    print x" | python

or (as commented by 1_CR) with Python 3:

python3 -c "print(*'StackOver',sep='n')"

You can use the fold (1) command. It is more efficient than grep and sed.

$ time grep -o . <bigfile >/dev/null



real    0m3.868s

user    0m3.784s

sys     0m0.056s

$ time fold -b1 <bigfile >/dev/null



real    0m0.555s

user    0m0.528s

sys     0m0.016s

$

One significant difference is that fold will reproduce empty lines in the output:

$ grep -o . <(printf "AnBnnCnnnDn")

A

B

C

D

$ fold -b1 <(printf "AnBnnCnnnDn")

A

B



C





D

$ 

You can handle multibyte characters like:

<input 

dd cbs=1 obs=2 conv=unblock |

sed -e:c -e '/^.*$/!N;s/n//;tc'

Which can be pretty handy when you're working with live input because there's no buffering there and a character is printed as soon it is whole.

You may use word boundaries also..

$ perl -pe 's/(?<=.)(B|b)(?=.)/n/g' <<< "StackOver"

S

t

a

c

k

O

v

e

r

In bash:

This works with any text and with only bash internals (no external utility called), so, should be fast on very short strings.

str="Stéphane áàéèëêếe"



[[ $str =~ ${str//?/(.)} ]]

(set -- "${BASH_REMATCH[@]:1}"; IFS=$'n'; echo "$*")

Output:

S

t

é

p

h

a

n

e



á

à

é

è

ë

ê

ế

e

If it is ok to change IFS and to change the positional parameters, you can also avoid the sub-shell call:

str="Stéphane áàéèëêếe"

[[ $str =~ ${str//?/(.)} ]]

set -- "${BASH_REMATCH[@]:1}"

IFS=$'n'

echo "$*"

s=stackoverflow;



$ time echo $s | fold -w1                                                                                                                                          

s                                                                                                                                                                          

t                                                                                                                                                                          

a                                                                                                                                                                          

c                                                                                                                                                                          

k                                                                                                                                                                          

o                                                                                                                                                                          

v

e

r



real    0m0.014s

user    0m0.000s

sys     0m0.004s

updates
here is the hacky|fastest|pureBashBased way !

$ time eval eval printf '%s\\n' \${s:{0..$((${#s}-1))}:1}

s

t

a

c

k

o

v

e

r



real    0m0.001s

user    0m0.000s

sys     0m0.000s

for more awesomeness

function foldh () 

{ 

    if (($#)); then

        local s="$@";

        eval eval printf '%s\\n' \"\${s:{0..$((${#s}-1))}:1}\";

    else

        while read s; do

            eval eval printf '%s\\n' \"\${s:{0..$((${#s}-1))}:1}\";

        done;

    fi

}

function foldv () 

{ 

    if (($#)); then

        local s="$@";

        eval eval echo \"\${s:{0..$((${#s}-1))}:1}\";

    else

        while read s; do

            eval eval echo \"\${s:{0..$((${#s}-1))}:1}\";

        done;

    fi

}

read -a var <<< $(echo "$yourWordhere" | grep -o "." | tr 'n' ' ')

this will split your word and store it in array var.

for x in $(echo "$yourWordhere" | grep -o '.')

do

    code to perform operation on individual character $x of your word

done