(written 16:22 Saturday 14 August 2021 JST)

I like all my URLs to be as human readable as possible.

I also like having the date in the filename of my photos.

For a while I tried to solve it on my phone, but haven’t found a way to get photos named with the date instead of just DSC_nnnn.jpg for an ever increasing value of nnnn.

Today I searched for things like append exif date filename bash and add exif date filename perl to find this date appending BASH one-liner:

for f in *; do mv -- "$f" "$f-$(stat -c %Y "$f" | date +%Y%m%d)"; done

However, for me (running Pop!OS), the above just renames the files with today’s date. It seems that | date is ignoring the portion coming from stat

The same question has an answer that (was updated(!) and) actually works for me. Here is Perl’s rename used to append file date to filename

rename -n 'BEGIN {use Date::Format; use File::Basename};
       die $! unless -f $_;
       my ($filename,$dirs,$suffix) = fileparse($_,qr/\.[^.]*/);
       next if (m/-\d{8}${suffix}$/);
       my $ts=(stat($_))[9];
       my $dt=time2str("%Y%m%d",$ts);
       s/${suffix}$/-${dt}${suffix}/;' *.txt

Above, -n means it shows us the plan. In this case, to change DSC_1163.txt -> DSC_1165.txt-20210808

Then with a few tweaks, I made it the format I want: DSC_1163.jpg -> 2021_aug_08_DSC_1163.jpg

rename  'BEGIN {use Date::Format; use File::Basename};
       die $! unless -f $_;                                      # skip if file DNE
       my ($filename,$dirs,$suffix) = fileparse($_,qr/\.[^.]*/); # determine the filename
       next if (m/^d{4}_/);                                      # skip if 4 digits and underscore are already front of filename (4 digit year)
       my $ts=(stat($_))[9];                                     # get the modification date
       my $dt=lc(time2str("%Y_%b_%d",$ts));                      # convert date to lowercase yyyy_mmm_dd format
       s/${filename}/${dt}_${filename}/;' *.*                    # tell rename what to do