Bash: Copying IPTC data

[Dotan Cohen]

I have a bunch of pictures that I need to copy IPTC data from one
field to another. I understand that the exiftool utility and I
installed it, but I cannot get it to do what I need (I'm no computer
guru). I need the IPTC feild #118 ( $iptc["2#118"][0] in PHP ) to be
copied to the IPTC feild #025 ( $iptc["2#025"][0] in PHP ). What bash
command would do that on hundreds of photos in a recursive directory
structure? I've no bash experience but I know enough php to look at it
and understand it, if it is possible to use the tool via PHP. Thanks
in advance.

Dotan Cohen
http://what-is-what.com