appending a text to the end of nth line without creating a newline

Question

I have a file A.txt and when I try to append a text to end of N^th line, it's printing by creating a new line, is there any command which will print in the same line without creating a newline?

A.txt

hi all       
how r u  
hows going

I want to a a string to the line N^th line ( line 2 in this example)

hi all   
how r u friend   
hows going

when I try the command I am getting in google, it's coming like below

$ cat a.txt
hi all  
how r u   
friend   
hows going

Answer 1

You can do it using sed as

sed '2s/.*/& friend/' a.txt

2s indicates that you want to substitute on line 2. .* will capture the entire line while & will print the line followed by new text.

If you want to update the file at the same time, you can use -i option with sed.

Answer 2

with awk:

awk 'NR==2{ $0=$0 " friend" }1' infile >output

NR==2 means second line of input, $0 represent the current input line, 1 at the end, outputs the current input line with any changes made on it or not.