using '$ compress.sh --file ./main.pdf'

pdf-compress.sh

#!/bin/bash

# Default values
FILE=""
QUALITY="/screen"

# Parse arguments
while [[ "$#" -gt 0 ]]; do
    case $1 in
        --file) FILE="$2"; shift ;;
        *) echo "Unknown parameter passed: $1"; exit 1 ;;
    esac
    shift
done

if [[ -z "$FILE" ]]; then
    echo "Usage: $0 --file <input.pdf>"
    exit 1
fi

if [[ ! -f "$FILE" ]]; then
    echo "File not found: $FILE"
    exit 1
fi

OUT_FILE="${FILE%.pdf}_compressed.pdf"

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=$QUALITY \
   -dNOPAUSE -dQUIET -dBATCH -sOutputFile="$OUT_FILE" "$FILE"

echo "Compressed PDF saved as $OUT_FILE"