Substitute and concatenate

[SimoneUe]

Hi,
I am still learning my ropes 

So far I can substitute text (I only want first names of the creators in the description field):
exiftool -overwrite_original '-Description<${Creator;s/ .*//g}'

I also know how to concatenate text:
exiftool -title<Mfg=$make'

Now I would like to combine the two, but somehow I struggle with the syntax. I tried different options, e.g.
exiftool -overwrite_original '-Description<${Caption-Abstract "Foto: " Creator;s/ .*//g}'

But as soon as I use the curly bracket, I cannot concatenate, without them, I cannot substitute.

Any help much appreciated

[StarGeek]

You only need to use braces when a tag name includes advanced formatting (${Creator;s/ .*//g}) or when it bumps up against other text (xXx${Creator}xXx).  You don't put anything else inside the braces that's not advanced formatting.

In your example, Caption-Abstract doesn't bump up against other text and no advanced formatting is being done to it, so it doesn't need braces, though it isn't hurt by doing so.  So separate each item in your concatenation:
exiftool -overwrite_original '-Description<$Caption-Abstract "Foto: " ${Creator;s/ .*//g}'

[SimoneUe]

Thanks, now I understand