How to append text at the end of each line (in-place) using sed or awk?-CodePudding

Existing table(sam.txt):

 36419 36418
 36418 36417
 36417 36416
 36416 36415

Desired output:

 36419 36418 1
 36418 36417 2
 36417 36416 3
 36416 36415 3

I want to append 1,2,3,4 as extra column. I have tried below sed command but I cannot loop line number $NUMBER as gives syntax error?

linecount=$(wc -l < sam.txt)
for (( NUMBER=1; NUMBER<=linecount; NUMBER   ))
do  
   sed -i "$NUMBERs/.*/& $b/" sam.txt
done

Update: Removed vertical bars between cells as it was causing confusion. I kept that vertical bars to render as HTML table but it didn't load as intended.

CodePudding user response：

This replies to the original question.

Instead of running sed multiple times, generate a single sed script and run that just once.

#! /bin/bash
lines=$(wc -l < "$1")
{
    echo '1s/$/C/'
    echo '2s/$/----/'
    for ((n=3; n<=lines;   n)) ; do
        echo $n's/$/'$((n-2))/
    done
    echo 's/$/|/'
} | sed -f- "$1"

CodePudding user response：

In awk $0 gives the whole line and you can add text as needed.We declare a variable a that we increment before using it which means that it is one on the first line. We then print the whole line a space the variable a

we run:

~/tests $ cat sam.txt | awk '{   a; print $0 " " a  }'

Which outputs

36419 36418 1
36418 36417 2                                
36417 36416 3
36416 36415 4

CodePudding user response：

$ awk '{print $0, NR}' sam.txt
36419 36418 1
36418 36417 2
36417 36416 3
36416 36415 4

If you want to modify the original file then with GNU awk:

awk -i inplace '{print $0, NR}' sam.txt

or with any awk:

awk '{print $0, NR}' sam.txt > tmp && mv tmp sam.txt

That last script is what gawk, sed, perl, ruby, etc. do behind the scenes anyway, none of them really do "inplace" editing, they all internally use a temp file.