Question

4

How to uppercase first letter of the first word in each sentence using shell script?

rated 0 times [ 4] [ 0] / answers: 1 / hits: 10987 / 1 Year ago, mon, january 9, 2023, 6:03:15

I am trying to capitalize each first letter of the first word in each sentence from a txt file called input.txt and I want this input file to be a argument of the shell script

 ./script.sh input.txt

sample input file:

i am Andrew. you are Jhon. here we are, forever.

result file:

I am Andrew. You are Jhon. Here we are, forever.

A special case. What if our text is (related to @RaduRadeanu answer)

i am andrew. you

are jhon. here we are

forever

the result would be:

I am andrew. You

Are jhon. Here we are

Forever.

So it convert to uppercase each first word of each sentence and also each first word of new line. How do we skip over uppercase first word of new line?

So the correct result must be:

I am andrew. You

are jhon. Here we are

forever.

What if the sentence closes in "?" or "!" ???

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rvousnove

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3 Years ago

answered 1 Year ago tiowift · Accepted Answer

sed command is very powerful to edit files from shell scripts. With its help you can edit however you want a text file. These being said, the following script can do what you wish:

#!/bin/bash



#check if a file is given as argument

if [ $# -ne 1 ];then

  echo "Usage: `basename $0` FILE NAME"

  exit 1

fi



sed -i 's/^s*./U&E/g' $@         #capitalize first letter from a paragraf/new line

sed -i 's/[.!?]s*./U&E/g' $@    #capitalize all letters that follow a dot, ? or !

For your special case, things became slightly:

#!/bin/bash



#check if a file is given as argument

if [ $# -ne 1 ];then

  echo "Usage: `basename $0` FILE NAME"

  exit 1

fi



sed -i '1s/^s*./U&E/g' $@  #capitalize first letter from the file

sed -i 's/.s*./U&E/g' $@  #capitalize all letters that follow a dot



#check if the a line ends in dot, ? or ! character and 

#if yes capitalize first letter from the next line

next_line=0

cat $@ | while read line ;do

  next_line=$[$next_line+1]

  lastchr=${line#${line%?}}

  if [ "$lastchr" = "." ] || [ "$lastchr" = "!" ] || [ "$lastchr" = "?" ]; then

    sed -i "$[$next_line+1]s/^s*./U&E/g" $@

  fi

done

Also, you can consult this tutorial: Unix - Regular Expressions with SED to see how to work in these situations.