Question

I’m trying to search and replace a string in all files matched by grep:

grep -n 'foo' * will give me output in the form:

[filename]:[line number]:[text] 

For each file returned by grep, I’d like to modify the file by replacing foo with bar.

Answer 1

Do you mean search and replace a string in all files matched by grep?

perl -p -i -e 's/oldstring/newstring/g' `grep -ril searchpattern *` 

Edit

Since this seems to be a fairly popular question thought I’d update.

Nowadays I mostly use ack-grep as it’s more user-friendly. So the above command would be:

perl -p -i -e 's/old/new/g' `ack -l searchpattern` 

To handle whitespace in file names you can run:

ack --print0 -l searchpattern | xargs -0 perl -p -i -e 's/old/new/g' 

you can do more with ack-grep. Say you want to restrict the search to HTML files only:

ack --print0 --html -l searchpattern | xargs -0 perl -p -i -e 's/old/new/g' 

And if white space is not an issue it’s even shorter:

perl -p -i -e 's/old/new/g' `ack -l --html searchpattern` perl -p -i -e 's/old/new/g' `ack -f --html` # will match all html files