$ perl -V

[...]

  @INC:
    /etc/perl
    /usr/local/lib64/perl5/5.26.2/x86_64-linux
    /usr/local/lib64/perl5/5.26.2
    /usr/lib64/perl5/vendor_perl/5.26.2/x86_64-linux
    /usr/lib64/perl5/vendor_perl/5.26.2
    /usr/local/lib64/perl5
    /usr/lib64/perl5/vendor_perl
    /usr/lib64/perl5/5.26.2/x86_64-linux
    /usr/lib64/perl5/5.26.2

##</code><code>##

$ ls -al /usr/lib/perl5/vendor_perl/5.26.2/Image/
total 468
drwxr-xr-x  3 root root   4096 2019-05-16 02:15:48 ./
drwxr-xr-x 17 root root   4096 2019-05-16 02:22:43 ../
drwxr-xr-x  4 root root   4096 2019-05-16 02:15:48 ExifTool/
-r--r--r--  1 root root 352517 2019-05-16 02:15:38 ExifTool.pm
-r--r--r--  1 root root 100000 2019-05-16 02:15:38 ExifTool.pod

##</code><code>##

$ perl pdf2john.pl file.pdf
Can't locate ExifTool.pm in @INC (you may need to install the ExifTool module) (@INC contains: ./lib /etc/perl /usr/local/lib64/perl5/5.26.2/x86_64-linux /usr/local/lib64/perl5/5.26.2 /usr/lib64/perl5/vendor_perl/5.26.2/x86_64-linux /usr/lib64/perl5/vendor_perl/5.26.2 /usr/local/lib64/perl5 /usr/lib64/perl5/vendor_perl /usr/lib64/perl5/5.26.2/x86_64-linux /usr/lib64/perl5/5.26.2) at pdf2john.pl line 39.
BEGIN failed--compilation aborted at pdf2john.pl line 39.

##</code><code>##

$ perl -I /usr/lib64/perl5/vendor_perl/5.26.2/Image/ pdf2john.pl file.pdf
Name "ExifTool::configFile" used only once: possible typo at pdf2john.pl line 36.
Name "ExifTool::langs" used only once: possible typo at pdf2john.pl line 771.
Name "ExifTool::charsetName" used only once: possible typo at pdf2john.pl line 589.
Name "ExifTool::langName" used only once: possible typo at pdf2john.pl line 771.
Can't locate object method "new" via package "ExifTool" at pdf2john.pl line 403.