Ghostscript /a command-line PDF processor/

Ghostscript is a free command-line program that can be used to add bookmarks, annotations, information, etc. to a pdf file.

Configuration

Frequently used gs options can be saved in an environment variable as default:

export GS_OPTIONS="-dSAFER -dBATCH -dNOPAUSE -sDEVICE=pdfwrite"

They can be overwritten by command line options.

This way, the command to combine PDF files can be shortened from

gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=combined.pdf file1.pdf file2.pdf

to

gs -o combined.pdf file1.pdf file2.pdf

where, -o is a short form of -sOutputFile=.

Convert pdf to pdf/a

pdf/a has all fonts embedded in the file. According to a stackoverflow post, the following command can be used to achieve this:

gs -dPDFA -dBATCH -dNOPAUSE -sProcessColorModel=DeviceRGB
   -sDEVICE=pdfwrite -sPDFACompatibilityPolicy=1
   -sOutputFile=output.pdf input.pdf

If you see error messages like

GPL Ghostscript 9.52: Annotation set to non-printing,
 not permitted in PDF/A, annotation will not be present in output file

Try to change -sPDFACompatibilityPolicy=1 to -dPDFACompatibilityPolicy=1, as explained here.

Extract Pages From a PDF

Set range of pages:

gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER \
   -sPageList=1,3,5-8 \
   -sOutputFile=outfile.pdf 100p-inputfile.pdf

One page per file:

gs -sDEVICE=pdfwrite -dSAFER -o outname.%d.pdf input.pdf

Or using pdftk:

pdftk pingpass.pdf cat 1-enddown output ping.pass.pdf

Reduce PDF file size

According to an article online, one can change PDF settings to reduce files size:

gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=out.pdf in.pdf

Available settings to optimize the file size include

• PDFSETTINGS=/screen (screen-view-only quality, 72 dpi images)
• PDFSETTINGS=/ebook (low quality, 150 dpi images)
• PDFSETTINGS=/printer (high quality, 300 dpi images)
• PDFSETTINGS=/prepress (high quality, color preserving, 300 dpi imgs)
• PDFSETTINGS=/default (almost identical to /screen)

Add bookmarks

Ref.: thechriskent.com, ubuntu forums.

Create a simple text file with a random name, for example, bookmarks. Put the following into this file.

[/PageMode /UseOutlines /DOCVIEW pdfmark
[/Page 1  /Title (Prologue) /OUT pdfmark
[/Page 5  /Title (Chapter 1) /Count 2 /OUT pdfmark
[/Page 5    /Title (Section 1.1) /OUT pdfmark
[/Page 9    /Title (Section 1.2) /OUT pdfmark
[/Page 18   /Title (Section 1.2) /OUT pdfmark
[/Page 27 /Title (Chapter 2) /OUT pdfmark

The first line enables the display of the bookmark sidebar in a pdf viewer. The rest adds bookmarks with titles on individual specified pages.

Run the following command to use this file:

gs -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=out.pdf in.pdf bookmarks

The command can be re-run to change the existing bookmarks. To remove bookmarks, one can try

pdf2ps input.pdf
ps2pdf input.ps

The file size may change after this operation.

Another option is to use pdftk:

pdftk A=example.pdf cat A1-end output nobookmarks.pdf

To install pdftk in mac:

brew install pdftk-java

It is installed in /usr/local/Celler/pdftk-java.