change_slideshow_duration.sh

#from: http://superuser.com/questions/175509/can-i-change-the-speed-of-slideshows-in-os-x

# Define variable, to save typing:
plist=/System/Library/PrivateFrameworks/Slideshows.framework/Versions/A/Resources/Content/EffectDescriptions

# make a backup copy:
cp -iv $plist.plist $HOME/Desktop/

# confirm backup copy is valid: MD5 checksums should match for both files
md5 $plist.plist $HOME/Desktop/EffectDescriptions.plist

# Take a look at the data structure before changing, to compare afterward
defaults read $plist JustASlide

# Set new value for slideshow duration: (in this case, 2 seconds)
sudo defaults write $plist JustASlide -dict-add mainDuration -int 2

# Fix permissions: `defaults` recreates the file with 0600 permissions
sudo chmod -v 0644 $plist.plist

# Double check the edit was successful
defaults read $plist JustASlide