Shell scripting question about cut

JimBass · 10-10-2005, 01:35 PM

Hello all!

I am piecing together a little script to convert all .wav files in all directories below the current one, and convert them into mp3 files. As my shell scripting sucks, I need a little help with the cut command. I have pieced together this script from some found here on linuxquestions:

Code:

#!/bin/bash

 find . -name *.wav > wavlist
 for i in $(cat wavlist)
 do
 ORIG=$j
 DEST=$(ls $j | cut -d "." -f 1).mp3
 lame -h -b 192 $ORIG $DEST
 echo "done converting $j, removing.."
 rm $j
 rm wavlist
 done

The problem is that the cut command removes everything past the period (.), but my list of files from line 2 has things in the form:

Code:

./directory/another/another/file.wav

I want it ot cut at the period before wav, but the script correctly cuts at the period that starts the line, and that doesn't pass the correct info to the lame encoder. I see that the -d "." option in cut uses a period as a delimiter, but how can I get it to perform the cut at the second period rather than the first?

Thanks for the help!

Peace,
JimBass

Vookimedlo · 10-10-2005, 01:57 PM

try basename (man basename)

Code:

DEST=$(basename $j .wav).mp3

JimBass · 10-10-2005, 02:21 PM

Thanks, but basename doesn't do what I wanted. It dtrips the extension nicely, but it also strips the leading directories, which I need. Printing the output of the script with your basename line gives this:

Code:

jim@musicbox:~/Tori_Amos$ ./script
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3
 .wav.mp3

Thanks though, if it just stripped but left the directory info, it would be ideal.

I see that you can specifiy a number of chars for cut to cut into, is there a switch to make it cut 3 chars from the end of a line?

Peace,
JimBass

anomie · 10-10-2005, 02:36 PM

Try

Code:

DEST=.$( ls $i | cut -d '.' -f '2' ).mp3

P.S. Your iterator is $i. Why are you referring to $j?

anomie · 10-10-2005, 02:40 PM

One more thing: It would be wise to add an exit status check after the lame program runs so that you're not deleting files that didn't get converted.

Code:

lame -h -b 192 $ORIG $DEST
if [[ $? -ne 0 ]] 
  then echo "Did not convert. Bailing out now..."
  exit 1
fi

Or some such.

JimBass · 10-10-2005, 03:05 PM

The iterator had been i, then I mostly converted it to j, and obviously missed an important one! Thanks for the help! It works well now. I added your saftey bailout, as that fdoes seem like a fine idea. Now the only issue is setting some type of control so that it only tries to remove wavlist.txt once, rather than each time it goes through te $j loop.

Code:

#!/bin/bash

 find . -name *.wav > wavlist.txt
 for j in $(cat wavlist.txt)
 do
 ORIG=$j
 DEST=.$(ls $j | cut -d "." -f 2).mp3

 lame -h -b 192 $ORIG $DEST
        if [[ $? -ne 0 ]]
        then echo "Did not convert. Bailing out now..."
        exit 1
        fi
 echo "done converting $j, removing.."
 rm $j
 rm wavlist.txt
 done

Thanks soo much for everyone's help!

Peace,
JimBass

anomie · 10-10-2005, 03:22 PM

Quote:

Now the only issue is setting some type of control so that it only tries to remove wavlist.txt once, rather than each time it goes through te $j loop.

Put the

Code:

rm wavlist.txt

on the line after

Code:

done

(i.e. after the loop is finished).

JimBass · 10-10-2005, 03:26 PM

I had thought done was for the entire script, not just the loop. Thanks again man! I really need to get my scripting together. Thank you for the insight, it helps me to understand what is happening and why.

Peace,
JimBass

jschiwal · 10-20-2005, 11:24 PM

Consider using variable substitution.

Something like:

lame -h -b 192 "$j" "${j%.wav}.mp3"

If you might have a mixture of .wav and .WAV files,
lame -h -b 192 "$j" ".${j%.[wW][aA][vV]}.mp3"

This method is closer to your cut command:
lame -h -b 192 "$j" ".${j%.*}.mp3"

I put quotes around the variables in the case when a variable has either whitespace or a special meta character. You may also want to change the value of the IFS variable to the \n character.

Otherwise, a space one of the lines would result in $j being assigned to only the first part of the line instead of the entire line.

Another small item, just because one conversion failed, I don't think that would be a valid reason to abort the entire loop. Perhaps this would work:

lame -h -b 192 "$j" ".${j%.*}.mp3" || rm .${j%.*}.mp3 ; echo "could not convert $j"