How to loop through files in subdirectories? - bash

Question

I'm trying to convert a bunch of .aac files to .mp3 files in separate subdirectories in a directory. This is the code I've written:
for dir in */
do
OUTPUT_DIR=./mp3
mkdir "$OUTPUT_DIR"
for i in *.aac;
do name=`echo "$i" | cut -d'.' -f1`
echo "$name"
ffmpeg -i "$i" -vn -ar 44100 -ac 2 -b:a 192k "$OUTPUT_DIR/${name}.mp3"
done
done
However this just try to run the commands in the outside directory and gives an error. I'm new at bash so it might be a very simple mistake I'm not seeing.

Answer 1

How to loop through files in subdirectories?
Read ex How to loop through a directory recursively to delete files with certain extensions
This is the code I've written:
Check your scripts with http://shellcheck.net
Do not use `. Use $(...) instead.
To get file name and dir see basename and dirname commands. Your name=echo "$i" | cut -d'.' -f1 will fail when directory has a dot.
Use printf "%s\n" "$i" or in bash <<<"$i" here string instead echo "$i" |. See ex. https://unix.stackexchange.com/questions/65803/why-is-printf-better-than-echo .
Prefer lower case variables in your scripts.
so it might be a very simple mistake I'm not seeing.
You are not changing the direcotry at all. You need to cd somewhere to that dir and then cd - back (or pushd + popd). But just reference directories relative to your current dir anyway. Maybe something along:
for dir in ./*/; do
# create the directory in dir
output_dir="./$dir/mp3"
mkdir "$output_dir"
# find files aac inside $dir/
for i in "$dir"/*.aac; do
name=$(basename "$i" .acc)
echo "$name"
ffmpeg -i "$i" -vn -ar 44100 -ac 2 -b:a 192k "$output_dir/${name}.mp3"
done
done

Answer 2

You may want to use find to recursively find all files in all subdirectories of a directory.
Here's an example (it assumes you also want to recreate the subdirectories in the output directory).
OUTPUT_DIR=./mp3
for item in $(find . -type f -name *.aac); do
name="$(basename $item .aac)"
subdir="$(dirname $item)"
mkdir -p "$OUTPUT_DIR/$subdir"
ffmpeg -i "$name" -vn -ar 44100 -ac 2 -b:a 192k "$OUTPUT_DIR/$subdir/$name.mp3"
done