Output in CSV format using AWK command

Question

I have a input.txt file with following format:

Name  age  number       address
mark  23   89756342192   chennai
david 40   70214789023   delhi

How do I create a CSV file from a TXT file as per the following example? Thanks.

mark,23,89756342192,chennai
david,40,70214789023,delhi

Below is the script i have written

printrep.sh

#!/bin/sh
Headers=["Name","Age","Phone","Address"];
count=$(wc -l < $name)
i=0;
echo "Headers[0] + ' , ' +Headers[1]+ ' , ' +Headers[2] + ' , ' +Headers[3] + ' , ' +Headers[4]";
while [ $i -lt $count ]
do
        read line | awk FS=' ' OFS="," '{print $0}'
        i=`expr $i + 1`
done

The above code is unable to display the output. And i Can't figure what is wrong. Please help I am a beginner to shell scripting

Answer 1

bash: the IFS variable is key here. This is bash specific for the use of arrays and read -a

IFS=,
while IFS=$' \t' read -ra fields; do echo "${fields[*]}"; done < input.txt

awk: very terse: $1=$1 rewrites the current line using the output field separator, and 1 to print the line.

awk '{$1=$1}1' OFS=, input.txt

miller: this requires the input file to not have empty lines: convert from "pretty-print" format to csv

mlr --p2c cat input.txt

This also correctly handles commas in the input:

$ cat input.txt
Name  age  number        address
mark  23   89756342192   chennai
david 40   70214789023   delhi
alice 24   42            paris,texas

$ mlr --p2c cat input.txt
Name,age,number,address
mark,23,89756342192,chennai
david,40,70214789023,delhi
alice,24,42,"paris,texas"

Answer 2

There are bunch of ways:

cut --output-delimiter="," -c1-6,7-11,12-25,26- < file
tr -s " " "," <file
sed -e "s/  */,/g" <file

Answer 3

sed -r -i 's/\s+/,/g' file.txt

output

cat file.txt 
Name,age,number,address
mark,23,89756342192,chennai
david,40,70214789023,delhi