find, xargs: execute chain of commands for each file - bash

Question

I am sorry if the question title is not informative enough. Please feel free to suggest a better variant.
I want to perform the following task:
In a directory I have a number of files that are photos in JPEG format. I want to extract from EXIF the dates when those photos were taken, create a new directory for each date, and move a file to the relevant directory.
(EXIF date and time have the format YYYY:MM:DD hh:mm:ss, and I want the directory names to be formatted as YYYY-MM-DD, that's why I use sed)
I kind of know how to perform each of those tasks separately, but failed to put them together. I spent some time investigating how to execute commands using find with -exec or xargs but still failed to understand how to properly chain everything.
Finally I was able to fulfil my task using two commands:
find . -name '*.jpg' -exec sh -c "identify -format %[exif:DateTimeOriginal] {}
| sed 's/ [0-9:]*//; s/:/-/g' | xargs mkdir -p" \;
find . -name '*.jpg' -exec sh -c "identify -format %[exif:DateTimeOriginal] {}
| sed 's/ [0-9:]*//; s/:/-/g; s/$/\//' | xargs mv {}" \;
But I do not like the duplication, and I do not like -exec sh -c. Is there the right way to do this in one line and without using -exec sh -c?

Answer 1

Rather than focusing on one-liners, a better solution would be to put the logic into a script which makes it easy to execute and test. Put this in a file called movetodate.sh:
#!/usr/bin/env bash
# This script takes one or more image file paths
set -e
set -o pipefail
for path in "$#"; do
date=$(identify -format %[exif:DateTimeOriginal] | sed 's/ [0-9:]*//; s/:/-/g')
dest=$(dirname "$path")/$date
mkdir -p "$dest"
mv "$path" "$dest"
done
Then, to invoke it:
find . -name '*.jpg' -exec ./movetodate.sh {} +

Answer 2

It is easily done with exiftool:
exiftool "-Directory<DateTimeOriginal" -d %Y-%m-%d *.jpg
For example, the command transforms a layout like this:
.
├── a.jpg (2013:10:17 10:01:00)
└── b.jpg (2012:08:07 16:11:15)
to this:
.
├── 2012-08-07
│   └── b.jpg
└── 2013-10-17
└── a.jpg
If you still want to use identify, the commands can be rewritten as follows:
script=$(cat <<'SCRIPT'
d=$(
d=$(identify -format "%[exif:DateTimeOriginal]" "$0" 2>/dev/null) || exit $?
d=${d:0:10}
printf '%s/%s' "$(dirname "$0")" "${d//:/-}"
) || exit $?
mkdir -p "$d" && mv -v "$0" "$d"
SCRIPT
)
find "$dir" -name '*.jpg' -exec bash -c "$script" {} \;
Note the use of $0 variable within the script. We pass the {} placeholder to the script as the first argument.
The script can easily be transformed to accept multiple arguments (paths) with the help of a for file in "$#" loop. In this case the \; character should be replaced with +. However, if you have a large number of files exceeding the $(getconf ARG_MAX) limit, you will need either xargs, or processing the files one by one as shown in the script above. The same considerations are applied to the exiftool command.

Answer 3

With parallel you do not need the script but would instead do:
doit() {
path="$1"
date=$(identify -format %[exif:DateTimeOriginal] | sed 's/ [0-9:]*//; s/:/-/g')
dest=$(dirname "$path")/$date
mkdir -p "$dest"
mv "$path" "$dest"
}
export -f doit
find . -name '*.jpg' | parallel doit