Shell script to change the modification date of a PSD file to the EXIF data within

date2exifdate.sh

# !/bin/sh
#
# date2exifdate shell script
# (tested on bash only)
# (c) 2022 by Gwyneth Llewelyn. Most rights reserved.
#
# Licensed under a MIT License (see https://gwyneth-llewelyn.mit-license.org/)
#
#
# Purpose: Change the modification date of a PSD file to the EXIF data within
#
# Rationale: Some stupid cloud storage systems (either on local NAS or remote servers...),
# when restoring files to a local directory, sometimes 'forget' the original date, and,
# instead, just place the date of the full sync. This is annoying since previously all files
# would be (correctly) sorted by modification date... and all that information will be lost.
#
# A partial solution is to read the original modification date from the EXIF or XMP headers and change
# the Unix modification date to be the same. This is particularly easy to do on PSD files (even ancient
# versions of Photoshop would properly tag everything with EXIF tags), but quite hard on other formats,
# especially when they're meant to be used on the Web, where shaving off a few extra bytes is so crucial.
#
# In my use-case, I tend to have a 'master' PSD file, and a series of images, in different formats and sizes, 
# with pretty much the same name as the 'master' PSD file. The series of commands below will not only change
# the PSD but also all files that have the same common basename.
#
# Obviously none of the rest will be changed, and this script isn't recursive, either. Caveat utilitor!
# 
# Preconditions: exiftool needs to be installed
# On Debian/Ubuntu this is trivial to install
# On other platforms, make sure you do have Perl installed; a correctly-configured CPAN
# will also do wonders to deal with dependency packages :-)
# The code below is very wordy and chatty; feel free to get rid of all unnecessary debugging information
# for a cleaner output

let i=0; 
for f in *.psd; 
do 
  echo $i:"$f(unstripped)"; 
  fstripped=$(basename -s .psd "$f");
  originalDate=$(exiftool -p '${ModifyDate#;DateFmt("%Y%m%d%H%M.%S")}' "$fstripped".psd);
  echo $originalDate;
  touch -t $originalDate "$fstripped".*;
  ls -l "$fstripped".*;
  let i=$i+1;
done