Find and replace {} in sed

The problem

Replacing all instances of vcr: {} with vcr: { record: :new_episodes }, in all files below spec/features.

Normally this find -exec can come to the rescue, so a reasonable approach might be:

$ find spec/features/ -type f -exec sed -i 's#vcr: {}#vcr: { record: :new_episodes }#' {} \;

Pro-tip: change the delimiter to #

Unfortunately we run in to trouble here: It just so happens that {} is the sequence find's -exec switch uses to substitute in filenames.

Well, surely we can just escape the {} through find, right?

$ find spec/features/ -type f -exec sed -i 's#vcr: \{\}#vcr: { record: :new_episodes }#' {} \;`
sed: -e expression #1, char 45: Invalid content of \{\}

Not quite. Now the \{\} are being passed straight through to sed, including the \s, and unfortunately when sed sees escaped {}s it assumes them to be a consecutive occurrence matcher.

The solution

Sometimes it's best to just ditch -exec altogether, and use the ever versatile xargs:

$ find spec/features/ -type f -print0 | xargs -0 sed -i 's#vcr: {}#vcr: { record: :new_episodes }#'

Dave Tapley

Programmer