CODEWITHSUNDEEP
bash
Hamishm
Hamishm

Reputation: 21

Inserting new numbered lines into existing text document using bash

I have a document resembling this format (with many more lines):

abc
def
hij
klm
nop

I need the output file to look like this:

>1
abc
>2
def
>3
hij
>4
klm
>5
nop

Basically, inserting a header with a number count before the start of each existing line. I've been experimenting using the sed command but so far without any success. Can anybody offer a suggestion on how to achieve this using Bash?

Upvotes: 0

Views: 52

Answers (3)

James Brown
James Brown

Reputation: 37464

Using nl, number lines of files:

$ nl -s $'\n' -w 1 file
1
abc
2
def
3
hij
4
klm
5
nop

man nl:

-s, --number-separator=STRING
       add STRING after (possible) line number

-w, --number-width=NUMBER
       use NUMBER columns for line numbers

Upvotes: 0

Sonny
Sonny

Reputation: 3183

A solution with awk

$ awk '{print ">"NR "\n"$0}' 1.txt
>1
abc
>2
def
>3
hij
>4
klm
>5
nop

Upvotes: 2

KuboMD
KuboMD

Reputation: 684

Simple and readable solution: Iterate, increment, output.

Storing output in a file called output.txt:

header=1                           #Header is num to insert
for item in `cat lines.txt`;       #loop through your other file
do
        echo $header >> output.txt #Insert header
        echo $item >> output.txt   #Insert line from file
        header=$((header+1))       #Increment the header
done

Gives you an output that looks like:

$cat output.txt
1
egg
2
steak
3
cheese
4
chicken
5
asparagus

Still Simple, slightly less readable solution:

header=1
for item in `cat lines.txt`;
do
        echo -e "$header\n$item" >> output.txt #Use echo -e to interpret newline character.
        header=$((header+1))
done

Gives the same output:

  $cat output.txt
    1
    egg
    2
    steak
    3
    cheese
    4
    chicken
    5
    asparagus

Upvotes: 0

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