I am going through the >3000 pictures we took in Antarctica, and noticed that some of them were way out of order. It turns out that one of the cameras' clocks was set 12 hours off. Then I realized the other camera was set to Pacific time anyway, so really it was five hours off.
A few minutes of searching around later, I found jhead, a command-line JPEG header tool with a very convenient function:
jhead -ta+5:00 *.jpg
This adds five hours to the Date Taken of all the JPG files in a directory. Spiffy. A shout out to Matthias Wandel for making this free tool available. His pipe organ looks pretty neat too! There’s something about computer folks and pipe organs…