Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

The manual for aufs makes several references to something called a "whiteout", but it's not clear to me what this is.

What is a whiteout and why would one exist?

share|improve this question
add comment

1 Answer

up vote 5 down vote accepted

It is how the union file system supports deleting from a union where the underlying file to be deleted resides on a read-only file system.

Say you have

  • /bin (read-only)
  • /usr/bin (read-only)
  • /home/USERNAME/bin (read-write)

all union mounted together in /bin (read-write).

And you do rm /bin/ls.

It would place a whiteout for ls in /home/USERNAME/bin, which makes it look like /bin/ls has been deleted.

See State of the unionfs for a good read and a full explanation.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.