Something like this?

#! perl -sw
my $data ='doc123/print doc456/read doc789/print doc145/print doc123/r
+ead ';

my @events = qw(print read);

for (@events) {
    my $count = 1;
    $data =~ s/($_)/$1.$count++/ge;
}

print $data;

__END__
# Output
C:\test>198864
doc123/print1 doc456/read1 doc789/print2 doc145/print3 doc123/read2
C:\test>
[download]