command notations like ${DateTimeOriginal}

[fiveyears]

Hello,

I've read something like this:
exiftool '-IPTC:DateCreated<${EXIF:DateTimeOriginal}+01:00' file

and this does work, but where does the variable ${EXIF:DateTimeOriginal} come from, it is not a bash variable but one can use it??

thanx

fiveyears

[Phil Harvey]

See the section on the -tagsFromFile option in the application documentation:

            An extension of the redirection feature allows strings involving
            tag names to be used on the right hand side of the "<" symbol with
            the syntax "'-DSTTAG<STR'", where tag names in STR are prefixed
            with a "$" symbol.  See the -p option for more details about this
            syntax.  Strings starting with a "=" sign must insert a single
            space after the "<" to avoid confusion with the "<=" operator
            which sets the tag value from the contents of a file.  A single
            space at the start of the string is removed if it exists, but all
            other whitespace is preserved.

- Phil