Pretty Practicable PDF Tricks In Linux

I still don’t have quite a lot of time to write a more or less decent technology or philosophy or science/math related post, but I just want to put this on my blog for the sake of reference  again (as most, if not all, of my blog entries).

My Dilemma

I have a copy of a pdf file from which I want to share some parts only to my lab exercise partner (for reasons I can’t exactly divulge in the public Internet). So I Google around how to manipulate, specifically to  pluck/extract specific pages from a pdf file, and still output the extracted files as pdf file/s themselves. Then I found pdftk. Fantastic tool. Really.

Why Is It Fantastic?

Here are a few reasons why:

For such a small (more or less) package (3408kB in my Ubuntu 8.10 installation) you can:

Pdftk can join and split PDFs; pull single pages from a file; encrypt and decrypt PDF files; add, update, and export a PDF’s metadata; export bookmarks to a text file; add or remove attachments to a PDF; fix a damaged PDF; and fill out PDF forms. In short, there’s very little pdftk can’t do when it comes to working with PDFs.

Also,

Developer Sid Steward describes pdftk as the PDF equivalent of an “electronic staple remover, hole punch, binder, secret decoder ring, and X-ray glasses.”  Pdftk can join and split PDFs; pull single pages from a file; encrypt and decrypt PDF files; add, update, and export a PDF’s metadata; export bookmarks to a text file; add or remove attachments to a PDF; fix a damaged PDF; and fill out PDF forms.

Swiss army knife of PDF files anyone? And thankfully, it’s free and open source. The above quotes are from linux.com, and a lot of us know that once something gets posted on linux.com, it’s more or less worthwhile to learn, more so to read at the very least. pdftk is a command line tool (sorry, but check out my further references below).

And installing it is just simply

sudo apt-get install pdftk

in my Ubuntu 8.04 and 8.10 installations. Again, quoting from linux.com, here are some very useful (at least to me) things you can do with pdftk. Of course, with a bit of knowledge in scripting or programming (bash, php, python etc) you can work wonders with this tool:

Joining files

Pdftk’s ability to join two or more PDF files is on par with such specialized applications as pdfmeld and joinPDF (discussed in this article). The command syntax is simple:

pdftk file1.pdf file2.pdf cat output newFile.pdf

cat is short for concatenate — that is, link together, for those of us who speak plain English — and output tells pdftk to write the combined PDFs to a new file.

Pdftk doesn’t retain bookmarks, but it does keep hyperlinks to both destinations within the PDF and to external files or Web sites. Where some other applications point to the wrong destinations for hyperlinks, the links in PDFs combined using pdftk managed to hit each link target perfectly.

Splitting files

Splitting PDF files with pdftk was an interesting experience. The burst option breaks a PDF into multiple files — one file for each page:

pdftk user_guide.pdf burst

I don’t see the use of doing that, and with larger documents you wind up with a lot of files with names corresponding to their page numbers, like pg_0001 and pg_0013 — not very intuitive.

On the other hand, I found pdftk’s ability to remove specific pages from a PDF file to be useful. For example, to remove pages 10 to 25 from a PDF file, you’d type the following command:

pdftk myDocument.pdf cat 1-9 26-end output removedPages.pdf

Updated Man page

For all the geeks and geekettes out there (no this sub heading is not sexist), here’s an updated man page from my Ubuntu 8.10 server installation:

PDFTK(1)                                                                                                                          PDFTK(1)

NAME
pdftk – A handy tool for manipulating PDF

SYNOPSIS
pdftk <input PDF files | – | PROMPT>
[input_pw <input PDF owner passwords | PROMPT>]
[<operation> <operation arguments>]
[output <output filename | – | PROMPT>]
[encrypt_40bit | encrypt_128bit]
[allow <permissions>]
[owner_pw <owner password | PROMPT>]
[user_pw <user password | PROMPT>]
[flatten] [compress | uncompress]
[keep_first_id | keep_final_id] [drop_xfa]
[verbose] [dont_ask | do_ask]
Where:
<operation> may be empty, or:
[cat | attach_files | unpack_files | burst |
fill_form | background | stamp | generate_fdf
dump_data | dump_data_fields | update_info]

For Complete Help: pdftk –help

DESCRIPTION
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
* 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 Stencil from PDF Forms
* Apply a Background Watermark or a Foreground Stamp
* Report PDF Metrics such as Metadata and Bookmarks
* Update PDF 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)

OPTIONS
A summary of options is included below.

–help, -h
Show summary of options.

<input PDF files | – | PROMPT>
A list of the input PDF files. If you plan to combine these PDFs (without using handles) then list files in  the  order  you
want  them  combined.  Use – to pass a single PDF into pdftk via stdin.  Input files can be associated with handles, where a
handle is a single, upper-case letter:

<input PDF handle>=<input PDF filename>

Handles are often omitted.  They are useful when specifying PDF passwords or page ranges, later.

For example: A=input1.pdf B=input2.pdf

[input_pw <input PDF owner passwords | PROMPT>]
Input PDF owner passwords, if necessary, are associated with files by using their handles:

<input PDF handle>=<input PDF file owner password>

If handles are not given, then passwords are associated with input files by order.

Most pdftk features require that encrypted input PDF are accompanied by the ~owner~ password. If the input PDF has no  owner
password,  then  the  user  password  must be given, instead.  If the input PDF has no passwords, then no password should be
given.

When running in do_ask mode, pdftk will prompt you for a password if the supplied password is incorrect or none was given.

[<operation> <operation arguments>]
If this optional argument is omitted, then pdftk runs in ’filter’ mode.  Filter mode takes only one PDF input and creates  a
new PDF after applying all of the output options, like encryption and compression.

Available operations are: cat, attach_files, unpack_files, burst, fill_form, background, stamp, dump_data, dump_data_fields,
generate_fdf, update_info. Some operations takes additional arguments, described below.

cat [<page ranges>]
Catenates pages from input PDFs to create a new PDF.  Page order in the new PDF is specified by the order  of  the  given
page ranges.  Page ranges are described like this:

<input PDF handle>[<begin page number>[-<end page number>[<qualifier>]]][<page rotation>]

Where  the  handle  identifies one of the input PDF files, and the beginning and ending page numbers are one-based refer‐
ences to pages in the PDF file, and the qualifier can be even or odd, and the page rotation can be N, S, E, W, L,  R,  or
D.

If the handle is omitted from the page range, then the pages are taken from the first input PDF.

The  even  qualifier  causes  pdftk  to  use only the even-numbered PDF pages, so 1-6even yields pages 2, 4 and 6 in that
order.  6-1even yields pages 6, 4 and 2 in that order.

The odd qualifier works similarly to the even.

The page rotation setting can cause pdftk to rotate pages and documents.  Each option sets the page rotation  as  follows
(in  degrees):  N:  0,  E: 90, S: 180, W: 270, L: -90, R: +90, D: +180. L, R, and D make relative adjustments to a page’s
rotation.

If no arguments are passed to cat, then pdftk combines all input PDFs in the order they were given to create the  output.

NOTES:
* <end page number> may be less than <begin page number>.
* The keyword end may be used to reference the final page of a document instead of a page number.
* Reference a single page by omitting the ending page number.
* The handle may be used alone to represent the entire PDF document, e.g., B1-end is the same as B.

Page Range Examples w/o Handles:
1-endE – rotate entire document 90 degrees
5 11 20
5-25oddW – take odd pages in range, rotate 90 degrees
6-1

Page Range Examples Using Handles:
Say A=in1.pdf B=in2.pdf, then:
A1-21
Bend-1odd
A72
A1-21 Beven A72
AW – rotate entire document 90 degrees
B
A2-30evenL – take the even pages from the range, remove 90 degrees from each page’s rotation
A A
AevenW AoddE
AW BW BD

attach_files <attachment filenames | PROMPT> [to_page <page number | PROMPT>]
Packs  arbitrary  files  into  a  PDF  using PDF’s file attachment features. More than one attachment may be listed after
attach_files. Attachments are added at the document level unless the optional to_page option is given, in which case  the
files are attached to the given page number (the first page is 1, the final page is end). For example:

pdftk in.pdf attach_files table1.html table2.html to_page 6 output out.pdf

unpack_files
Copies  all  of  the attachments from the input PDF into the current folder or to an output directory given after output.
For example:

pdftk report.pdf unpack_files output ~/atts/

or, interactively:

pdftk report.pdf unpack_files output PROMPT

burst  Splits a single, input PDF document into individual pages. Also creates a report named doc_data.txt which is the same  as
the  output  from dump_data.  If the output section is omitted, then PDF pages are named: pg_%04d.pdf, e.g.: pg_0001.pdf,
pg_0002.pdf, etc.  To name these pages yourself, supply a printf-styled format string via the output section.  For  exam‐
ple,  if  you  want  pages  named: page_01.pdf, page_02.pdf, etc., pass output page_%02d.pdf to pdftk.  Encryption can be
applied to the output by appending output options such as owner_pw, e.g.:

pdftk in.pdf burst owner_pw foopass

fill_form <FDF data filename | XFDF data filename | – | PROMPT>
Fills the single input PDF’s form fields with the data from an FDF file, XFDF file or  stdin.  Enter  the  data  filename
after fill_form, or use – to pass the data via stdin, like so:

pdftk form.pdf fill_form data.fdf output form.filled.pdf

After  filling  a  form, the form fields remain interactive unless you also use the flatten output option. flatten merges
the form fields with the PDF pages. You can use flatten alone, too, but only on a single PDF:

pdftk form.pdf fill_form data.fdf output out.pdf flatten

or:

pdftk form.filled.pdf output out.pdf flatten

If the input FDF file includes Rich Text formatted data in addition to plain text, then the Rich Text data is packed into
the form fields as well as the plain text.  Pdftk also sets a flag that cues Acrobat/Reader to generate new field appear‐
ances based on the Rich Text data.  That way, when the user opens the PDF, the viewer will create the Rich Text fields on
the  spot.   If the user’s PDF viewer does not support Rich Text, then the user will see the plain text data instead.  If
you flatten this form before Acrobat has a chance to create (and save) new field appearances, then the plain  text  field
data is what you’ll see.

background <background PDF filename | – | PROMPT>
Applies  a  PDF  watermark  to the background of a single input PDF.  Pass the background PDF’s filename after background
like so:

pdftk in.pdf background back.pdf output out.pdf

Pdftk uses only the first page from the background PDF and applies it to every page of  the  input  PDF.   This  page  is
scaled and rotated as needed to fit the input page.  You can use – to pass a background PDF into pdftk via stdin.

If  the input PDF does not have a transparent background (such as a PDF created from page scans) then the resulting back‐
ground won’t be visible — use the stamp feature instead.

stamp <stamp PDF filename | – | PROMPT>
This behaves just like the background feature except it overlays the stamp PDF page on top of the  input  PDF  document’s
pages.  This works best if the stamp PDF page has a transparent background.

dump_data
Reads  a  single, input PDF file and reports various statistics, metadata, bookmarks (a/k/a outlines), and page labels to
the given output filename or (if no output is given) to stdout.  Does not create a new PDF.

dump_data_fields
Reads a single, input PDF file and reports form field statistics to the given output filename or (if no output is  given)
to stdout.  Does not create a new PDF.

generate_fdf
Reads  a single, input PDF file and generates a FDF file suitable for fill_form out of it to the given output filename or
(if no output is given) to stdout.  Does not create a new PDF.

update_info <info data filename | – | PROMPT>
Changes the metadata stored in a single PDF’s Info dictionary to match the input data file. The input data file uses  the
same  syntax  as  the  output from dump_data. This does not change the metadata stored in the PDF’s XMP stream, if it has
one. For example:

pdftk in.pdf update_info in.info output out.pdf

[output <output filename | – | PROMPT>]
The output PDF filename may not be set to the name of an input filename.  Use  –  to  output  to  stdout.   When  using  the
dump_data  operation,  use output to set the name of the output data file. When using the unpack_files operation, use output
to set the name of an output directory.  When using the burst operation, you can use output to  control  the  resulting  PDF
page filenames (described above).

[encrypt_40bit | encrypt_128bit]
If an output PDF user or owner password is given, output PDF encryption strength defaults to 128 bits.  This can be overrid‐
den by specifying encrypt_40bit.

[allow <permissions>]
Permissions are applied to the output PDF only if an encryption strength is specified or an owner or user password is given.
If permissions are not specified, they default to ’none,’ which means all of the following features are disabled.

The permissions section may include one or more of the following features:

Printing
Top Quality Printing

DegradedPrinting
Lower Quality Printing

ModifyContents
Also allows Assembly

Assembly

CopyContents
Also allows ScreenReaders

ScreenReaders

ModifyAnnotations
Also allows FillIn

FillIn

AllFeatures
Allows the user to perform all of the above, and top quality printing.

[owner_pw <owner password | PROMPT>]

[user_pw <user password | PROMPT>]
If  an  encryption  strength  is  given but no passwords are supplied, then the owner and user passwords remain empty, which
means that the resulting PDF may be opened and its security parameters altered by anybody.

[compress | uncompress]
These are only useful when you want to edit PDF code in a text editor like vim or emacs.  Remove PDF page stream compression
by applying the uncompress filter. Use the compress filter to restore compression.

[flatten]
Use  this  option  to merge an input PDF’s interactive form fields (and their data) with the PDF’s pages. Only one input PDF
may be given. Sometimes used with the fill_form operation.

[keep_first_id | keep_final_id]
When combining pages from multiple PDFs, use one of these options to copy the document ID from either  the  first  or  final
input  document  into the new output PDF. Otherwise pdftk creates a new document ID for the output PDF. When no operation is
given, pdftk always uses the ID from the (single) input PDF.

[drop_xfa]
If your input PDF is a form created using Acrobat 7 or Adobe Designer, then it probably has XFA data.  Filling such  a  form
using  pdftk  yields  a PDF with data that fails to display in Acrobat 7 (and 6?).  The workaround solution is to remove the
form’s XFA data, either before you fill the form using pdftk or at the time you fill the  form.  Using  this  option  causes
pdftk to omit the XFA data from the output PDF form.

This  option  is  only  useful  when  running pdftk on a single input PDF.  When assembling a PDF from multiple inputs using
pdftk, any XFA data in the input is automatically omitted.

[verbose]
By default, pdftk runs quietly. Append verbose to the end and it will speak up.

[dont_ask | do_ask]
Depending on the compile-time settings (see ASK_ABOUT_WARNINGS), pdftk might prompt you for further input when it encounters
a  problem, such as a bad password. Override this default behavior by adding dont_ask (so pdftk won’t ask you what to do) or
do_ask (so pdftk will ask you what to do).

When running in dont_ask mode, pdftk will over-write files with its output without notice.

EXAMPLES
Decrypt a PDF
pdftk secured.pdf input_pw foopass output unsecured.pdf

Encrypt a PDF using 128-bit strength (the default), withhold all permissions (the default)
pdftk 1.pdf output 1.128.pdf owner_pw foopass

Same as above, except password ’baz’ must also be used to open output PDF
pdftk 1.pdf output 1.128.pdf owner_pw foo user_pw baz

Same as above, except printing is allowed (once the PDF is open)
pdftk 1.pdf output 1.128.pdf owner_pw foo user_pw baz allow printing

Join in1.pdf and in2.pdf into a new PDF, out1.pdf
pdftk in1.pdf in2.pdf cat output out1.pdf
or (using handles):
pdftk A=in1.pdf B=in2.pdf cat A B output out1.pdf
or (using wildcards):
pdftk *.pdf cat output combined.pdf

Remove ’page 13’ from in1.pdf to create out1.pdf
pdftk in.pdf cat 1-12 14-end output out1.pdf
or:
pdftk A=in1.pdf cat A1-12 A14-end output out1.pdf

Apply 40-bit encryption to output, revoking all permissions (the default). Set the owner PW to ’foopass’.
pdftk 1.pdf 2.pdf cat output 3.pdf encrypt_40bit owner_pw foopass

Join two files, one of which requires the password ’foopass’. The output is not encrypted.
pdftk A=secured.pdf 2.pdf input_pw A=foopass cat output 3.pdf

Uncompress PDF page streams for editing the PDF in a text editor (e.g., vim, emacs)
pdftk doc.pdf output doc.unc.pdf uncompress

Repair a PDF’s corrupted XREF table and stream lengths, if possible
pdftk broken.pdf output fixed.pdf

Burst a single PDF document into pages and dump its data to doc_data.txt
pdftk in.pdf burst

Burst a single PDF document into encrypted pages. Allow low-quality printing
pdftk in.pdf burst owner_pw foopass allow DegradedPrinting

Write a report on PDF document metadata and bookmarks to report.txt
pdftk in.pdf dump_data output report.txt

Rotate the first PDF page to 90 degrees clockwise
pdftk in.pdf cat 1E 2-end output out.pdf

Rotate an entire PDF document to 180 degrees
pdftk in.pdf cat 1-endS output out.pdf

NOTES
pdftk uses a slightly modified iText Java library (http://itextpdf.sourceforge.net/) to read and write  PDF.  The  author  compiled
this Java library using GCJ (http://gcc.gnu.org) so it could be linked with a front end written in C++.

The pdftk home page is http://www.accesspdf.com/pdftk/.

AUTHOR
Sid Steward (ssteward@accesspdf.com) maintains pdftk.

September 18, 2006                                                    PDFTK(1)

Comments, questions, and suggestions are always welcome as long as they’re calm and ruly 🙂

Further References

>>linux.com reference article

>>Main site for pdftk (including manual/documentation), a bit dated though

>> GUI for pdftk

Tags: Linux, linux.com, PDF, pdftk, split files, split pdf files