Bash – find the single largest file

Is that size as in file size, or size as in image dimensions?

In zsh, to see all .png files in the current directory and its subdirectories, sorted by increasing file size:

echo **/*.png(oL)

There's no convenient glob qualifier for grabbing every N files. Here's a loop that sets the array $a to contain every 50th file (starting with the largest).

a=() i=0
for x in **/*.png(OL); do
  ((i%50)) || a+=$x
  ((++i))
done
my-favorite-image-viewer $a

Without zsh or GNU find, there's no easy way of sorting find output by metadata (there's find -ls or find -exec ls or find -exec stat, but they might not work with files containing non-printable characters, so I don't like to recommend them). Here's a way to do it in Perl.

find . -name '*.png' |
perl -e '
    $, = "\n";  # separate elements by newlines in the output
    print  # print…
        sort {-s $a <=> -s $b}  # …sorted by file size…
            map {chomp;$_} <>  #…the input lines (with the newline bitten off)
'

And here's a way to view every 50th file (starting with the largest):

find . -name '*.png' |
perl -e '
    $, = "\n";
    exec "my-favorite-image-viewer",
        map {$i++ % 50 ? () : $_}  # every 50
            sort {-s $b <=> -s $a} map {chomp;$_} <>
'

Another approach would be to create symbolic links in a single directory, with names ordered by file size. In zsh:

mkdir tmp && cd tmp
i=1000000  # the extra 1 on the left ensures alignment
for x in ../**/*(oL); do
    ((++i))
    ln -s $x ${i#1}.png
done

With Perl:

mkdir tmp && cd tmp
find .. -name '*.png' |
perl -e '
    $, = "\n";
    for $x (sort {-s $a <=> -s $b} map {chomp;$_} <>) {
        symlink $x, sprintf("%06d", ++$i);
    }
'

The command you claim to be executing doesn't match the error message you're getting, but either way this answer should clarify some things.

First, note that if there are any files matching *jpg in the current directory, the pattern *jpg will be expanded on the command line of find. You need to quote the pattern to protect from that.

With the command you've given, what gets executed is something like

cd directory && mv -f file

But mv expects two arguments: a source file and a destination.

You need to pass a target directory, and since you're using -execdir, the target directory will be interpreted relative to each directory where there are .jpg files. Note that the directory must exist. If you want to move all .jpg files to a single directory, create it first, then run

find -iname '*.jpg' -execdir mv -f {} /common-destination-directory

If you want to move all files to a relative path, for example move them to the images subdirectory relative to where they are, you will need to create the directory first.

find -iname '*.jpg' -execdir mkdir -p images \; -execdir mv -f {} images \;

With GNU utilities (i.e. on Linux) you can optimize a little by running mv only once per directory:

find -iname '*.jpg' -execdir mkdir -p images \; -execdir mv -t images {} +