UNIX for Dummies Questions & Answers

Hi,

The following code finds the line containing fruits in test.txt and replaces instances of apple with banana.

Code:

   ed -s test.txt <<< $'/fruits/s/apple/banana/g\nw'

What I want to do is put variables in the place of fruits, apple and banana.

I have tried replacing ' with " to get the variables to expand, but to no avail.

Code:

ed -s accounts.txt <<< $"/$account/s/$balance/$newBalance/g\nw"

Also

Code:

ed -s accounts.txt <<< $"/${account}/s/${balance}/${newBalance}/g\nw"

And trying to echo them, but still no luck.


I'm using GNU bash, version 3.2.33(1)-release (i386-redhat-linux-gnu)

The $ in front of the string causes it to try to execute the string and feed its output into ed, not feed it into ed directly. Which is a new one on me. Shells are such weird things. cat <<< "asdf" works fine, as does cat <<< "$varname".

Thanks for taking the trouble to reply.
If anyone can think of any easy way to do what I want to do then let me know.
Curently traawling through the mountain of find and replace postings on the forum.

Simply open file, find Word in line then replace word1 with word2. Then write change to file.
Word is a unique field in file so will only exist on one line. Word1 will only be present once per line.

cheers

Nick

Code:

 sed -i "/$address/s/$pat1/$pat2/" accounts.txt

Where address finds you the line, then pat1 is replaced by pat2. Only occurs once per line.