Substitution only on last matching line (perl one-liner)

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I have multiple files of the form

version 'aaa'
other 'bbb'
another 'ccc'
version 'ddd'
onemore 'eee'

Some have one version, others have multiple; same with the other keys, but the values never repeat. I’m using, as part of a bigger bash function, a perl one-liner to modify values

modify_value() {
  key_to_modify="$1"
  new_value="$2"

  perl -i'' -pe "s|^(\s*)${key_to_modify} .*|\1${key_to_modify} ${new_value}|" "${file}"
}

This works great to an extent. I can do

modify_value "onemore" "fff"

And it will be correctly replaced in the text file. However, where it breaks down is where I have multiple keys with the same name (such as the aforementioned version), as this change will be made in all of them. In my particular case, I want the modification to be make always in the last case.

Since values are never repeated, so far what I have is

modify_value() {
  key_to_modify="$1"
  new_value="$2"

  last_key=$(cat "${file}" | grep "^\s*${key_to_modify}" | tail -1 | perl -pe 's/^\s*//')

  perl -i'' -pe "s|^(\s*)"${last_key}"|\1${key_to_modify} ${new_value}|" "${file}"
}

This works, but is a bit inelegant. Would it be possible to leverage the perl one-liner to act only on the latest occurrence of the match, instead?

asked 21 secs ago

user137369

622

Substitution only on last matching line (perl one-liner)