Как объединить несколько файлов PDF в один файл? [дубликат]

Да, pdftk, в pdftk пакет.

От man pdftk страница:

   If PDF is electronic paper, then pdftk is an electronic staple-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses.  Pdftk is a simple tool for doing everyday things with PDF documents.  Use it to:

   * Merge PDF Documents or Collate PDF Page Scans
   * Split PDF Pages into a New Document
   * Rotate PDF Documents or Pages
   * Decrypt Input as Necessary (Password Required)
   * Encrypt Output as Desired
   * Fill PDF Forms with X/FDF Data and/or Flatten Forms
   * Generate FDF Data Stencils from PDF Forms
   * Apply a Background Watermark or a Foreground Stamp
   * Report PDF Metrics, Bookmarks and Metadata
   * Add/Update PDF Bookmarks or Metadata
   * Attach Files to PDF Pages or the PDF Document
   * Unpack PDF Attachments
   * Burst a PDF Document into Single Pages
   * Uncompress and Re-Compress Page Streams
   * Repair Corrupted PDF (Where Possible)