How to Use the Command 'cpdf' (with Examples)

cpdf is a powerful command-line tool for manipulating PDF files in various ways. It allows users to perform numerous operations on PDF documents, such as selecting specific pages, merging files, viewing bookmarks, and encrypting or decrypting content. It is especially useful for anyone who regularly works with PDFs and seeks efficient, automated solutions for their PDF management tasks. Let’s explore some use cases to understand how cpdf can be leveraged effectively.

Select Pages from a PDF

Code:

cpdf path/to/source_document.pdf 1-3,6 -o path/to/destination_document.pdf

Motivation: There can be situations where you need to extract specific pages from a large PDF, such as producing a shorter version of a report for certain stakeholders or only selecting the most relevant sections of a document for study. This use case demonstrates how to extract particular pages efficiently.

Explanation:

• cpdf path/to/source_document.pdf: Specifies the source PDF file from which you want to extract pages.
• 1-3,6: This indicates the range and specific pages to be extracted, which in this case are pages 1, 2, 3, and 6.
• -o path/to/destination_document.pdf: Denotes the output file path for the new PDF containing only the selected pages.

Example Output: A new PDF file named destination_document.pdf is created, containing only the pages numbered 1, 2, 3, and 6 from the source document.

Merge Two Documents

Code:

cpdf -merge path/to/source_document_one.pdf path/to/source_document_two.pdf -o path/to/destination_document.pdf

Motivation: Often, there is a need to consolidate information from multiple PDFs into a single comprehensive document, such as for compiling research papers or merging reports. This command efficiently merges two PDF files into one.

Explanation:

• -merge: This option indicates that the purpose is to merge files.
• path/to/source_document_one.pdf path/to/source_document_two.pdf: These are the paths of the PDF files to be merged.
• -o path/to/destination_document.pdf: Specifies the name and path of the merged output PDF.

Example Output: A single PDF named destination_document.pdf containing the contents of both source PDF files is produced.

Show Document Bookmarks

Code:

cpdf -list-bookmarks path/to/document.pdf

Motivation: Bookmarks in PDFs provide a navigation aid for readers and maintain hierarchical information about document structure. Checking bookmarks can be essential for quick access to different sections, especially in large documents.

Explanation:

• -list-bookmarks: With this argument, cpdf lists all the bookmarks available in the document.
• path/to/document.pdf: This is the path of the PDF file whose bookmarks you want to examine.

Example Output: A list of bookmarks present in document.pdf is displayed, providing insights into the document’s hierarchical structure.

Split a PDF into Chunks

Code:

cpdf -split path/to/document.pdf -o path/to/chunk%%%.pdf -chunk 10

Motivation: Splitting a large PDF into smaller, manageable chunks can be necessary for easier distribution, processing, or faster loading on devices. This use case outlines a way to automatically split a document into portions of a desired length.

Explanation:

• -split path/to/document.pdf: Points to the PDF that needs splitting.
• -o path/to/chunk%%%.pdf: This specifies the format of the output files, with %%% serving as placeholders for sequential numbering.
• -chunk 10: Instructs cpdf to divide the document into chunks each containing 10 pages.

Example Output: Separate files named chunk001.pdf, chunk002.pdf, etc., are created, each containing 10 pages from document.pdf.

Encrypt a PDF with Passwords

Code:

cpdf -encrypt 128bit fred joe path/to/source_document.pdf -o path/to/encrypted_document.pdf

Motivation: There is often a need to protect sensitive information contained in PDF files. This command demonstrates encrypting a document to ensure that it remains confidential and access is restricted.

Explanation:

• -encrypt 128bit fred joe: This applies 128-bit encryption. fred is set as the owner password, allowing full permissions, while joe restricts content permissions.
• path/to/source_document.pdf: Identifies the PDF file that is to be encrypted.
• -o path/to/encrypted_document.pdf: Designates the output file path for the encrypted document.

Example Output: An encrypted version of the PDF named encrypted_document.pdf is produced, requiring a password for access.

Decrypt a PDF

Code:

cpdf -decrypt path/to/encrypted_document.pdf owner=fred -o path/to/decrypted_document.pdf

Motivation: Decrypting a PDF becomes necessary when you need to access or modify the content of a document protected by owner restrictions. This use allows the removal of encryption by providing the owner password.

Explanation:

• -decrypt: Indicates that the intention is to remove encryption.
• path/to/encrypted_document.pdf: Supplies the path of the document to be decrypted.
• owner=fred: Provides the owner password necessary for decryption.
• -o path/to/decrypted_document.pdf: Determines the output path for the decrypted document.

Example Output: A decrypted PDF named decrypted_document.pdf is generated, free from password restrictions.

Show Document Annotations

Code:

cpdf -list-annotations path/to/document.pdf

Motivation: Annotations such as comments and highlights in a PDF can be crucial for collaborative projects and review processes. This command aids in extracting all annotations so that users can quickly review them.

Explanation:

• -list-annotations: Lists all annotations present in the PDF.
• path/to/document.pdf: Specifies the document whose annotations you want to view.

Example Output: A detailed list of annotations within document.pdf is rendered, showcasing various notes and comments present.

Add Metadata to a PDF

Code:

cpdf -set-metadata path/to/metadata.xml path/to/source_document.pdf -o path/to/destination_document.pdf

Motivation: Metadata helps organize and identify documents by embedding information like author name, creation date, and keywords. Adding metadata is essential for document management systems and archival purposes.

Explanation:

• -set-metadata path/to/metadata.xml: Fetches metadata from an XML file and sets it in the PDF.
• path/to/source_document.pdf: Indicates the source PDF to which metadata is added.
• -o path/to/destination_document.pdf: Specifies the output path for the newly updated PDF document.

Example Output: A PDF named destination_document.pdf is created, enriched with metadata from metadata.xml.

Conclusion:

The ‘cpdf’ command-line tool is a versatile and robust way to manage and manipulate PDF documents. Whether you’re extracting pages, merging files, encrypting data, or adding metadata, cpdf offers an effective solution for all these tasks. Its broad range of functions makes it an essential tool for anyone who deals with PDFs regularly.