Usage

Lang: sh 
# Copy metadata form existing file
$ exiftool -tagsFromFile src_file.pdf dst_file.pdf

# Edit metadata of new file
$ exiftool -Author="TBD" -Producer="TBD" -Creator="TBD" \
  -CreationDate="TBD" -ModDate="TBD" drawing.pdf

# Remove a tag
$ exiftool file.pdf -Creator=

# Same date for file creation and modification
$ exiftool "-filemodifydate<createdate"