Add a prefix string to beginning of each line

Question

Hi,

I have a file below :

line1
line2
line3

And I want to get

prefixline1
prefixline2
prefixline3

I could write a ruby script but it is better if I don't need to.

EDIT: prefix will contains / , it is a path , /opt/workdir/ for example.

Answer 1

sed -e 's/^/prefix/' file

If you want to edit the file in-place:

sed -i -e 's/^/prefix/' file

If you want to create a new file:

sed -e 's/^/prefix/' file >file.new

If prefix contains /, you can use any other character not in prefix, or escape the /, so the sed command becomes: 's#^#/opt/workdir#', or 's/^/\/opt\/workdir/'.

Answer 2

awk '{print "prefix"$0}' file > new_file

Answer 3

using the shell

#!/bin/bash
prefix="something"
file="file"
while read -r line
do
 echo "${prefix}$line"
done <$file > newfile
mv newfile $file