mv_calibre_junk

#!/usr/bin/env bash

die() { printf %s "${@+$@$'\n'}" 1>&2 ; exit 1 ; }
see() ( { set -x; } 2>/dev/null ; "$@" )

# what/why: ebooks often come in archive-file sets which (I've taken awhile to
# realize) often include calibre-format-translated versions of the ebook in
# formats I don't care about (azw* and mobi); these are just deadweight
# consumers of disk space: if I need the format, I'm perfectly able to use
# calibre to generate a version of the file in the needed format; otherwise,
# I want to delete them before they start consuming server (especially
# backup) storage.
#
# Rather than delete such files, this script moves these files to a
# _calibre_junk subdir; higher level scripts are free to rm -rf this dir
#
die() { printf %s "${@+$@$'\n'}" 1>&2 ; exit 1 ; }
see() ( { set -x; } 2>/dev/null ; "$@" )
dieifnotinpath() { command -v "$1" >/dev/null || die "$1 not in PATH"; }
dieifnotinpath pdfinfo
dieifnotinpath find_calibre_binary

ebookmeta="$(find_calibre_binary ebook-meta)" || die

fn_exists() { declare -F "$1" > /dev/null; }  # https://stackoverflow.com/a/85932

calibre_produced() { "$ebookmeta" "$1" | grep -q '^Book Producer.\+calibre' ; }  # `ebook-meta` does not display "Book Producer ..." metadata for PDF files (though calibre WRITES it to produced PDFs!)
calibre_produced_pdf() { pdfinfo  "$1" | grep -qP '^Producer:\s+calibre\s'  ; }

mkdir -p _calibre_junk || die "mkdir failed"

# https://stackoverflow.com/a/26349346  variant of  https://stackoverflow.com/a/8489394
azwmobi() (
   find . -maxdepth 1 -type f \( -iname '*.azw*' -o -iname '*.mobi' \) -print0 | while IFS= read -r -d '' fnm; do
      if calibre_produced "$fnm" ; then
         see mv -- "$fnm" _calibre_junk
         fi
      done
   )

all() (  # note that we exclude .medtype.pdf files from consideration
   find . -maxdepth 1 -type f \( -iname '*.azw*' -o -iname '*.mobi' -o -iname '*.pdf' \) ! -iname '*.medtype.pdf' -print0 | while IFS= read -r -d '' fnm; do
      ext="${fnm##*.}"
      cpfx=calibre_produced ; if fn_exists "${cpfx}_$ext" ; then cpfx="${cpfx}_$ext" ; fi
    # echo "$ext $cpfx  $fnm"
    # if mt="${fnm/%pdf/medtype.pdf}" && [[ -f "$mt" ]] && "$cpfx" "$fnm" ; then
      if                   "$cpfx" "$fnm" ; then
         see mv -- "$fnm" _calibre_junk
         fi
      done
   )

"${1:-all}"  # run scan