Today i was trying to merge different pdf files. So i came to know about this wonderful tool pdftk in Linux .
Use of pdftk :
- Merge PDF Documents
- Split PDF Pages into a New Document
- Rotate PDF Pages or Documents
- Decrypt Input as Necessary (Password Required)
- Encrypt Output as Desired
- Fill PDF Forms with FDF Data or XFDF Data and/or Flatten Forms
- Apply a Background Watermark or a Foreground Stamp
- Report on PDF Metrics such as Metadata, Bookmarks, and Page Labels
- 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)
To install pdftk via apt
apt-get install pdftk
To install pdftk via yum,
yum install pdftk
How to use
Merge Two or More PDFs into a New Document
pdftk 1.pdf 2.pdf 3.pdf cat output 123.pdf
or (Using Handles):
pdftk A=1.pdf B=2.pdf cat A B output 12.pdf
or (Using Wildcards):
pdftk *.pdf cat output combined.pdf
Split Select Pages from Multiple PDFs into a New Document
pdftk A=one.pdf B=two.pdf cat A1-7 B1-5 A8 output combined.pdf
Rotate the First Page of a PDF to 90 Degrees Clockwise
pdftk in.pdf cat 1E 2-end output out.pdf
Rotate an Entire PDF Document’s Pages to 180 Degrees
pdftk in.pdf cat 1-endS output out.pdf
Encrypt a PDF using 128-Bit Strength (the Default) and Withhold All Permissions (the Default)
pdftk mydoc.pdf output mydoc.128.pdf owner_pw foopass
Same as Above, Except a Password is Required to Open the PDF
pdftk mydoc.pdf output mydoc.128.pdf owner_pw foo user_pw baz
Same as Above, Except Printing is Allowed (after the PDF is Open)
pdftk mydoc.pdf output mydoc.128.pdf owner_pw foo user_pw baz allow printing
Decrypt a PDF
pdftk secured.pdf input_pw foopass output unsecured.pdf
Join Two Files, One of Which is Encrypted (the Output is Not Encrypted)
pdftk A=secured.pdf mydoc.pdf input_pw A=foopass cat output combined.pdf
Uncompress PDF Page Streams for Editing the PDF Code in a Text Editor
pdftk mydoc.pdf output mydoc.clear.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 Single Pages and Report its Data to doc_data.txt
pdftk mydoc.pdf burst
Report on PDF Document Metadata, Bookmarks and Page Labels
pdftk mydoc.pdf dump_data output report.txt
Nithin's Blog 
Great article on pdftk. Very helpful thank you!
I need to split a single page PDF into smaller (shorter typewritten pages). i have tried pdftk’s burst command on my linux partition but the result is a duplication of my original page. I need to split one pdf page into 3 pages of equal length for printing on letter size sheets without shrinking or scaling down. Is there a way to specify number of output pages when using ‘burst?
Pdftk from the input file just copies the content to output file and cant do very much to optimize or make it in equal length. So your input file and output will be similar ie if you have large documents as your input the output will also be similar. Any fonts embedded in pdf doc may end up in duplicating the output document.