Adjust Exif time of pictures

Sometimes after you come home from holidays you realize that you forgot to adjust the time of your digital camera. So all pictures might have a wrong date and/or time in the exif header. Fortunately it is pretty easy to fix that with linux:

jhead -ta10:11 *

=> Adds 10 hours and 11 minutes to the exif datetime of all files (that have exif headers) in the current folder

jhead -ta-10:11 *

=> Subtracts 10 hours and 11 minutes from the exif datetime of all files (that have exif headers) in the current folder