Programmatically resize Mac OS X Dock based on presence of external monitor

resize-dock-external-monitor.sh

#!/bin/bash
#
# Resizes the Mac OS X Dock based on whether or not an external monitor
# is connected.
#
# This script will need to be ran whenever the display configuration
# changes (that is, whenever a display is connected or disconnected).
# I use Stay[1] to do this.
#
# [1]: http://cordlessdog.com/stay/
#
#
# Copyright (C) 2013 Brad Feehan
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


# Default tilesize when monitor isn't detected
tilesize=46

# Description of the display shown by system_profiler (when connected)
online='^\s\+Online:\s\+\Yes$'

if [[ "$(/usr/sbin/system_profiler SPDisplaysDataType | grep "$online" | wc -l)" -ge 2 ]]; then
    # Tilesize for when two or more monitors are detected
    tilesize=66
fi

# Set the preference for tilesize in the .plist
/usr/bin/defaults write com.apple.dock tilesize -int "$tilesize"

# Restart Dock.app to apply configuration changes
killall -TERM Dock

exit 0