Replace multiple underscores in filename using bash script-CodePudding

Doing some reading here and here I found this solution to replace two underscores in filenames with only one using bash:

for file in *; do
  f=${file//__/_}
  echo $f
done;

However how do I most easily expand this expression to replace an arbitrary number of underscores with only one?

CodePudding user response：

Typically, it's going to be faster to just put your original code in a loop than to do anything else.

for file in *; do
  f=$file
  while [[ $f = *__* ]]; do
    f=${f//__/_}
  done
  echo "$f"
done

Even better, if you're on a modern shell release, you can enable extended globs, which provide regex-like functionality:

shopt -s extglob
for file in *; do
  f=${file// (_)/_}
  echo "$f"
done

CodePudding user response：

You could use a simple regex using sed

for file in *; do
  f=$(echo "$file" | sed -e 's/_\ /_/')
  echo "$f"
done;

This regex matches one or more underscores (_\ ) and substitutes them with only one (_)

CodePudding user response：

GNU tr has --squeeze-repeats:

$ echo foo_______bar | tr --squeeze-repeats _
foo_bar

If you're using BSD tr you can use -s instead:

$ echo foo_______bar | tr -s _
foo_bar