Tag names containing "/" symbols – how do you work with them?

[philbond87]

How would I use Exiftool to read or write to the tag:

Code Select Expand

[File] File Modification date/time

[StarGeek]

See FAQ #2.
"File Modification date/time" is not a tag name, it's a tag description.  Add the -s (short) option to see the actual tag name.

It can also be useful to add the -a (duplicates) option and the -G (-groupNames) option to make sure you see all the data and what groups they belong to (see FAQ #3).  My default command to view data always starts:
exiftool -G1 -a -s