Concatenate files with progress bar on GNU/Linux

When I download files form rapidshare or other file hosting sites I occasionally download movies that are splited into parts, and to watch the movie they need to be concatenated.

I came up with this bash function which I put in my .bashrc file:

function concat() {
  files=${@:1:$(($#-1))}
  cat $files | pv -s $(du -cb $files | tail -n1 | cut -d $'\t' -f1) > ${@: -1}
}

If you have files like Movie.avi.001…Movie.avi.020, to concatenate these files just type:

concat Movie.avi.* Movie.avi

And you’ll see progress bar when output file is created.