Mfcttrf

Did Lincoln tell Stowe "So you're the little woman that started this great war!"?

When did the Roman Empire fall according to contemporaries?

Is "take care'n of" correct?

Why are they 'nude photos'?

How did the hit man miss?

Graduate student with abysmal English writing skills, how to help

Was lunar module "pilot" Harrison Schmitt legally a "pilot" at the time?

How can I effectively communicate to recruiters that a phone call is not possible?

Why were Er and Onan punished if they were under 20?

Novel where a group of scientists in a spaceship encounter various aliens

A pyramid from a square

Maximum charterer insertion

How might the United Kingdom become a republic?

Shortest distance around a pyramid?

How to find the shape parameters of of a beta distribution given the position of two quantiles?

Why does my script create an extra character?

Why didn't Thanos kill all the Dwarves on Nidavellir?

Get ids only where one id is null and other isn't

Should disabled buttons give feedback when clicked?

How can one write good dialogue in a story without sounding wooden?

How can I deal with a player trying to insert real-world mythology into my homebrew setting?

ESTA: "Is your travel to the US occurring in transit to another country?" when going on a cruise

Professor falsely accusing me of cheating in a class he does not teach, two months after end of the class. What precautions should I take?

Why do players in the past play much longer tournaments than today's top players?

Why does my script create an extra character?

Replace character based on range of coordinatesHow to read from two input files using while loopHow to name a file in the deepest level of a directory treeReading character by character with bash readBash is automatically reloading (injecting) updates into a running script upon saving it: Why? Any practical use?Create an ASCII art table from tabular dataIs there a way to execute commands while getting user input?Reading char-by-char silently does not workread 1 or several lines in bash - make it work when pasting (in addition to typing manually)How can I print out the delimiter character and allow user to edit line while reading standard input?How to replace last occurence of a character?

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;

2

I know this isn't a good thing to do and/or a good solution but I was just messing around trying to answer this question and I came across the following problem.

The goal is to read the input file character by character and if the character is within the specified range, replace it.

Input:

NNNNN
NNNNN
NNNNN
NNNNN

Script:

#!/bin/bash
#set -x

input=~/tmp/in
declare -i count=0
low=$1
high=$2
new_char=$3

while IFS=$'n' read -r line; do
 while IFS= read -rn1 char; do
 if ((count>=low)) && ((count<=high)); then
 printf '%s' "$new_char"
 else
 printf '%s' "$char"
 fi
 ((count++))
 done <<<"$(printf '%s' "$line")"
 echo
done <"$input"

Desired output (when run as: ./script.sh 10 13 P):

NNNNN
NNNNP
PPPNN
NNNNN

Actual output:

$ ./script.sh 10 13 P
NNNNN
NNNNPP
PPNNN
NNNNN

I'm not sure why it's seemingly creating a new character out of thin air on the 2nd line and not replacing the 13th character on the 3rd line. I've tried moving the ((count++)) statement to the beginning of the second while loop, I've tried starting at count=1, I've tried seemingly every combination of ((++count)) || count=$((count+1)) || ((count+1)). With varying results but all seem to add an extra character on the second line.

I've double checked that the input file has no trailing whitespace on any of the lines.

bash text-processing

share|improve this question

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  count must be 1 at the beginning or put ((count++)) at the beginning of the inner loop. Then if you use done < <(printf '%s' "$line") instead of done <<<"$(printf '%s' "$line")", it works as intended. I don't know why yet...
  
  – pLumo
  9 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  I think <<<"string" creates a temp file in the background, and bash is not stripping the trailing newline like command substitution does.
  
  – glenn jackman
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you run with set -x, you will see a printf %s '' at the end of every line except for on the line that becomes too long. This possibly means that your inner read returns an empty string at the end of each line.
  
  – Kusalananda♦
  9 hours ago
  

  
  
  
  

add a comment | 

2

I know this isn't a good thing to do and/or a good solution but I was just messing around trying to answer this question and I came across the following problem.

The goal is to read the input file character by character and if the character is within the specified range, replace it.

Input:

NNNNN
NNNNN
NNNNN
NNNNN

Script:

#!/bin/bash
#set -x

input=~/tmp/in
declare -i count=0
low=$1
high=$2
new_char=$3

while IFS=$'n' read -r line; do
 while IFS= read -rn1 char; do
 if ((count>=low)) && ((count<=high)); then
 printf '%s' "$new_char"
 else
 printf '%s' "$char"
 fi
 ((count++))
 done <<<"$(printf '%s' "$line")"
 echo
done <"$input"

Desired output (when run as: ./script.sh 10 13 P):

NNNNN
NNNNP
PPPNN
NNNNN

Actual output:

$ ./script.sh 10 13 P
NNNNN
NNNNPP
PPNNN
NNNNN

I'm not sure why it's seemingly creating a new character out of thin air on the 2nd line and not replacing the 13th character on the 3rd line. I've tried moving the ((count++)) statement to the beginning of the second while loop, I've tried starting at count=1, I've tried seemingly every combination of ((++count)) || count=$((count+1)) || ((count+1)). With varying results but all seem to add an extra character on the second line.

I've double checked that the input file has no trailing whitespace on any of the lines.

bash text-processing

share|improve this question

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  count must be 1 at the beginning or put ((count++)) at the beginning of the inner loop. Then if you use done < <(printf '%s' "$line") instead of done <<<"$(printf '%s' "$line")", it works as intended. I don't know why yet...
  
  – pLumo
  9 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  I think <<<"string" creates a temp file in the background, and bash is not stripping the trailing newline like command substitution does.
  
  – glenn jackman
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you run with set -x, you will see a printf %s '' at the end of every line except for on the line that becomes too long. This possibly means that your inner read returns an empty string at the end of each line.
  
  – Kusalananda♦
  9 hours ago
  

  
  
  
  

add a comment | 

I know this isn't a good thing to do and/or a good solution but I was just messing around trying to answer this question and I came across the following problem.

The goal is to read the input file character by character and if the character is within the specified range, replace it.

Input:

NNNNN
NNNNN
NNNNN
NNNNN

Script:

#!/bin/bash
#set -x

input=~/tmp/in
declare -i count=0
low=$1
high=$2
new_char=$3

while IFS=$'n' read -r line; do
 while IFS= read -rn1 char; do
 if ((count>=low)) && ((count<=high)); then
 printf '%s' "$new_char"
 else
 printf '%s' "$char"
 fi
 ((count++))
 done <<<"$(printf '%s' "$line")"
 echo
done <"$input"

Desired output (when run as: ./script.sh 10 13 P):

NNNNN
NNNNP
PPPNN
NNNNN

Actual output:

$ ./script.sh 10 13 P
NNNNN
NNNNPP
PPNNN
NNNNN

I'm not sure why it's seemingly creating a new character out of thin air on the 2nd line and not replacing the 13th character on the 3rd line. I've tried moving the ((count++)) statement to the beginning of the second while loop, I've tried starting at count=1, I've tried seemingly every combination of ((++count)) || count=$((count+1)) || ((count+1)). With varying results but all seem to add an extra character on the second line.

I've double checked that the input file has no trailing whitespace on any of the lines.

bash text-processing

share|improve this question

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

NNNNN
NNNNN
NNNNN
NNNNN

#!/bin/bash
#set -x

input=~/tmp/in
declare -i count=0
low=$1
high=$2
new_char=$3

while IFS=$'n' read -r line; do
 while IFS= read -rn1 char; do
 if ((count>=low)) && ((count<=high)); then
 printf '%s' "$new_char"
 else
 printf '%s' "$char"
 fi
 ((count++))
 done <<<"$(printf '%s' "$line")"
 echo
done <"$input"

NNNNN
NNNNP
PPPNN
NNNNN

$ ./script.sh 10 13 P
NNNNN
NNNNPP
PPNNN
NNNNN

share|improve this question

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

share|improve this question

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

asked 9 hours ago

Jesse_bJesse_b

17.5k33 gold badges4343 silver badges8484 bronze badges

2 Answers
2

active

oldest

votes

3

Here Strings seem to produce a newline at the end:

You can try and see the difference:

cat <<<"test"
cat <(printf '%s' "test")

So, you should use < <(printf '%s' "$line") instead of <<<"$(printf '%s' "$line")".

share|improve this answer

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

add a comment | 

2

I would write:

while IFS= read -r line; do
 for ((i=0; i<$#line; i++)); do
 char=$line:i:1
 ((count++))
 ((low <= count && count <= high)) && char=$new_char
 printf '%s' "$char"
 done
 echo
done <"$input"

share|improve this answer

edited 8 hours ago

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

add a comment | 

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "106"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f529584%2fwhy-does-my-script-create-an-extra-character%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

3

Here Strings seem to produce a newline at the end:

You can try and see the difference:

cat <<<"test"
cat <(printf '%s' "test")

So, you should use < <(printf '%s' "$line") instead of <<<"$(printf '%s' "$line")".

share|improve this answer

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

add a comment | 

3

Here Strings seem to produce a newline at the end:

You can try and see the difference:

cat <<<"test"
cat <(printf '%s' "test")

So, you should use < <(printf '%s' "$line") instead of <<<"$(printf '%s' "$line")".

share|improve this answer

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

add a comment | 

Here Strings seem to produce a newline at the end:

You can try and see the difference:

cat <<<"test"
cat <(printf '%s' "test")

So, you should use < <(printf '%s' "$line") instead of <<<"$(printf '%s' "$line")".

share|improve this answer

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

cat <<<"test"
cat <(printf '%s' "test")

share|improve this answer

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

answered 9 hours ago

pLumopLumo

6,6421313 silver badges2727 bronze badges

2

I would write:

while IFS= read -r line; do
 for ((i=0; i<$#line; i++)); do
 char=$line:i:1
 ((count++))
 ((low <= count && count <= high)) && char=$new_char
 printf '%s' "$char"
 done
 echo
done <"$input"

share|improve this answer

edited 8 hours ago

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

add a comment | 

2

I would write:

while IFS= read -r line; do
 for ((i=0; i<$#line; i++)); do
 char=$line:i:1
 ((count++))
 ((low <= count && count <= high)) && char=$new_char
 printf '%s' "$char"
 done
 echo
done <"$input"

share|improve this answer

edited 8 hours ago

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

add a comment | 

I would write:

while IFS= read -r line; do
 for ((i=0; i<$#line; i++)); do
 char=$line:i:1
 ((count++))
 ((low <= count && count <= high)) && char=$new_char
 printf '%s' "$char"
 done
 echo
done <"$input"

share|improve this answer

edited 8 hours ago

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

while IFS= read -r line; do
 for ((i=0; i<$#line; i++)); do
 char=$line:i:1
 ((count++))
 ((low <= count && count <= high)) && char=$new_char
 printf '%s' "$char"
 done
 echo
done <"$input"

share|improve this answer

edited 8 hours ago

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges

answered 9 hours ago

glenn jackmanglenn jackman

55k66 gold badges7676 silver badges115115 bronze badges