Replace a line in a text file

Question

Hello

I've a text file with a line

default_color acolor

and I want to replace this line with

default_color anothercolor

I don't know the first color and the second is contained in a variable. How can I do it in bash ?

Thank you

Answer 1

It is not pure bash but if you have other console tools, try something like

cat your_file | sed "s/default_color\ .*/default_color\ $VAR/"

Answer 2

You could use awk. The manual entry is here:

http://ss64.com/bash/awk.html

I won't write the regular expression necessary, as that will depend on your color format, but this will fit the bill. Best of luck.

Answer 3

use gawk

awk '$2=="defaultcolor"{$2="anothercolor"}1' file

or just bash shell and no external commands

while read -r line
do
 case "$line" in 
   *defaultcolor*) line=${line/defaultcolor/anothercolor}
 esac
 echo $line
done <"file"

Answer 4

Not really a bash solution, but you can do the replacement in-place, for any number of files, with perl:

perl -i -npe 's/default_color acolor/default_color another_color/' list_of_files