Thursday, May 12, 2022

Change metadata in PDF file using exiftool

To change the metadata in PDF files, use a command line tool called exiftool. This tool can manipulate metadata in many file types, but in this post we will focus on changing the metadata in a pdf file.

To install this tool in ubuntu, run below command
$ sudo apt install libimage-exiftool-perl -y

Then, use the exiftool command to list out all the metadata in a pdf file
$ exiftool mypdf.pdf

Some details like below will be shown
ExifTool Version Number         : 11.88
File Name                       : mypdf.pdf
Directory                       : .
File Size                       : 1 MB
File Modification Date/Time     : 2022:12:08 07:46:39+08:00
File Access Date/Time           : 2022:12:08 07:46:43+08:00
File Inode Change Date/Time     : 2022:12:08 07:46:39+08:00
File Permissions                : rw-rw-r--
File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.3
Linearized                      : No
Page Count                      : 15
XMP Toolkit                     : Image::ExifTool 11.88
Title                           : mypdf.pdf
Producer                        : Nitro PDF PrimoPDF
Create Date                     : 2022:09:30 16:57:06-08:00
Modify Date                     : 2022:09:30 16:57:06-08:00
Creator                         : PrimoPDF
Author                          : andre

To see just one tag, we can specify it when running exiftool. Let's say I want to see just the Author
$ exiftool -Author mypdf.pdf
Author                          : andre

To change the value of the tag, just provide the new value to the tag in the exiftool command. Let's say I want to change the author from andre to john
$ exiftool -Author=john mypdf.pdf

We can verify that the change has been implemented
$ exiftool -Author mypdf.pdf
Author                          : john

Once we are satisfied with the change, delete the original backup file that exiftool created prior to changing the metadata
$ rm mypdf.pdf_original

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