Replacing text in PDF

I recently found myself needing to replace some text in a PDF for confidentiality reasons. I tried LibreOffice and some other GUI applications, but they had problems with content sizing and canvas size. After searching online, a StackOverflow answer showed how to do it using the command-line PDFtk and sed. The answer warns that it doesn’t always work, but it did in my case, changing the text and not messing anything else up (that I could see).

I didn’t have PDFtk already, so I used MacPorts to install it: sudo port install pdftk. It actually said the port was broken, but the command was there and seemed to work fine.

I tested the commands from the above answer, but ran into a problem. Another StackOverflow answer gave me the solution: I had to set LANG=C to tell sed to treat the file as binary.

The commands then worked to do what I wanted. I put them together into a bash script for future use:

if [ "$#" -ne 4 ]; then
    echo "Usage: input.pdf 'string to replace' 'string replacement' output.pdf"
    exit 1

#--needed for encoding to be handled correctly on mac
#--uncompress, replace text, recompress, and remove temp files
pdftk $1 output _tmp12345.pdf uncompress \
&& sed -e "s/$2/$3/g" <_tmp12345.pdf >_tmp22345.pdf \
&& pdftk _tmp22345.pdf output $4 compress \
&& rm _tmp12345.pdf _tmp22345.pdf

It takes four arguments, shown in the “Usage” line echoed when you run it with less than four arguments.

I make no promises that it’ll work for your needs.