Automator replace text, 1st occurrence only

Question

using automator to rename audio files from a record date.
Not so much rename as name exchange.
The original files were wrongly named.
So what once was Audi L is now RF 3.
But there is also Mid Audi L that is also being changed.
Is there a way to limit the search to very specific text?

Answer 1

This will only replace text in a filename that starts with what you are searching for:
The Run Shell Script Action is:
for f in "$1"/*
do
     path=${f%/*}
     basename=${f##*/}
     nname=${basename/#$2/$3}
     if [ "$f" != "$path/$nname" ]; then
          mv "$f" "$path/$nname"
     fi
done
In  nname=${basename/#$2/$3}, the # is what determines that the search must start at the beginning of the filename