UNIX for Dummies Questions & Answers

I have gotten myself totally lost trying to sort this out and just need some help please..

I will have a multiple directories using the following naming convention with an undetermined number of files in each directory.

9780743582094_05of5_Accountable.wav

I need to batch rename all files grabbing the two digit number after the first underscore, and appending it to the end of the file name,with a preceding hyphen, before the extension.

The example: 9780743582094_05of5_Accountable.wav

Would become

9780743582094_05of5_Accountable-05.wav

I know sed or awk could work but I have not been using Linux/Unix for some time and really have burned out trying to remember this. Please show me the way with an explanation. I am using Ubuntu 10.04 and have the rename command available to me.

For those who are going to insist to see some effort on my part, sadly this is all I've got:

Code:

for i in `ls|grep -o '_[00-99].'|tr '_' '-'`; do echo $i;done

The reason i am doing this is to try and use a script that I found to batch convert wav files to .m4b audiobook format, but I first must convert to mp3. If anyone has a better suggestion to accomplish this, I would also love to hear about that. But first, I really need an answer to this sed issue because it is upsetting me.

Using parameter expansion:

Code:

for i in *_*_*.wav
do
  t=${i#*_}
  mv "$i" "${i%.*}-${t%%of*}.${i##*.}"
done

This works brilliantly, but please explain a bit.. Also why this is better than awk or sed..

Hi it is faster than awk or sed since no external programs need to be called from the shell to do the parsing..

I hope this helps. It can look a bit cryptic at first, but it really isn't that complicated..

Since $i will always contain files ending in .wav, this is equivalent in this case:

Code:

for i in *_*_*.wav
do
  t=${i#*_}
  mv "$i" "${i%.wav}-${t%%of*}.wav"
done

I have begun reading about parameter expansion.. Thanks so much, this is incredibly helpful.

Thanks! Good to hear. I noticed there was a mistake in the explanation and I made a correction..

S.