[m000]

That is called a sponge!

  SPONGE(1)                          moreutils                         SPONGE(1)

  NAME
         sponge - soak up standard input and write to a file

  SYNOPSIS
         sed '...' file | grep '...' | sponge [-a] file

  DESCRIPTION
         sponge reads standard input and writes it out to the specified file.
         Unlike a shell redirect, sponge soaks up all its input before writing
         the output file. This allows constructing pipelines that read from and
         write to the same file.