Bash: Batch Resize Images

Question

I'm working on a Bash script that will take an array of directories, iterate through it, create a directory named "processed" inside each directory, and run a command on each file within the directory. Here's my code (read the comment in the code to see what I'm stuck on). Any ideas?

#!/bin/bash

command -v convert >/dev/null 2>&1 || {
    echo >&2 "Convert is not installed. Aborting.";
    exit 1;
}

declare -a directories_to_process=(
    "$HOME/Desktop/Album 1"
    "$HOME/Desktop/Album 2"
    "$HOME/Desktop/Album 3"
);

for directory in "${directories_to_process[@]}"
do
    if [ -d "$directory" ]; then
        if [ ! -d "$directory/processed" ]; then
            mkdir "$directory/processed"
        fi

        # Insert code to run the following command on each file in $directory:
        #
        # convert $directory/$filename -resize 108x108^ -gravity center -extent 108x108 $directory/processed/$filename
    fi
done

UPDATE:

Here is the working script:

#!/bin/bash

command -v convert >/dev/null 2>&1 || {
    echo >&2 "Convert is not installed. Aborting.";
    exit 1;
}

directories_to_process=(
    "$HOME/Desktop/Album 1"
    "$HOME/Desktop/Album 2"
    "$HOME/Desktop/Album 3"
);

for directory in "${directories_to_process[@]}"
do
    [[ -d $directory ]] || continue

    mkdir -p "$directory/processed"

    for infile in "$directory"/*.jpg
    do
        outfile="$directory/processed/${infile##*/}"
        convert "$infile" \
                -resize '108x108^' \
                -gravity center \
                -extent 108x108 \
                "$outfile"
    done
done

Answer 1

Add this in the commented-out area:

for infile in "$directory"/*; do
  outfile="$directory/processed/${infile##*/}"
  convert "$infile" \
      -resize '108x108^' \
      -gravity center \
      -extent 108x108 \
      "$outfile"
done

A few other notes:

• Instead of nesting a great deal of logic inside of if [ -d "$directory" ], consider putting [[ -d $directory ]] || continue at the top of the loop to reduce the nesting depth. (Unlike [ ], quoting is not needed inside [[ ]] in this case).
• Instead of testing [ ! -d "$directory/processed" ] and using that to decide whether to create the directory, consider unconditionally running mkdir -p "$directory/processed", which will simply exit with a successful status if the directory already exists.
• Consider replacing command -v convert with type convert, which is somewhat better known than the command -v syntax but will have the same effect.
• You don't need the declare -a when declaring an array variable outside of a function; simply directories_to_process=( ... ) will work.