Created Pre-Consume Script Examples (markdown)

Pre-Consume-Script-Examples.md

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+This wiki page is a repository of example [pre-consume scripts](https://paperless-ngx.readthedocs.io/en/latest/advanced_usage.html#pre-consumption-script) contributed by the community.  As always, you should exercise caution when using a script and make sure you understand the code before using a script from the internet.
+
+
+## Removing Blank Pages
+
+- :warning: **This script modifies the original file**
+- Original source: https://github.com/paperless-ngx/paperless-ngx/discussions/668#discussioncomment-3936343
+
+```bash
+#!/usr/bin/env bash
+set -e -o pipefail
+export LC_ALL=C
+
+#IN="$1"
+IN="$DOCUMENT_SOURCE_PATH"
+
+PAGES=$(pdfinfo "$IN" | grep ^Pages: | tr -dc '0-9')
+THRESHOLD=0.002
+
+non_blank() {
+  for i in $(seq 1 $PAGES) ; do
+    PERCENT=$(gs -o -  -dFirstPage=${i} -dLastPage=${i} -sDEVICE=inkcov "${IN}" | grep CMYK | nawk 'BEGIN { sum=0; } {sum += $1 + $2 + $3 + $4;} END { printf "%.5f\n", sum } ')
+    if awk "BEGIN { exit !($PERCENT > $THRESHOLD) }"; then
+      echo $i
+    else
+      >&2 echo Color-sum is $PERCENT: will remove blank page $i of $IN
+    fi
+  done
+}
+
+NON_BLANK=$(non_blank)
+
+if [ -n "$NON_BLANK" ]; then
+  NON_BLANK=$(echo $NON_BLANK  | tr ' ' ",")
+  qpdf "$IN" --replace-input --pages . $NON_BLANK --
+fi
+```