Well, could you start by explaining what you’re trying to do?
Serial communications to upload compiled sketches and send/receive
text from the arduino in the monitor worked for me with no
special installation steps. I just ran the newest Arduino.app and selected the
proper Board and Serial Port.
Could be that the documentation you are reading is out of date.
On my Mountain Lion 2010 macbook pro, DYLD_LIBRARY_PATH is unset. To see all environment variables,
go to the terminal and type set.
To append something to an existing environment variable, you
would do something like the line below. This is assuming you’re using BASH,
the default Linux, Mac shell. Other shells have different syntax.
means add /newstuff to the end of what is currently in the variable called PATH.
If you just want to talk to an arduino over a serial link, ie. get sensor data or whatever your sketch is sending using Serial.print(), there is no need to use the Arduino IDE.
For example, at the terminal typing
spits out whatever is coming in on that serial device. (Your /dev/usbmodemXXXXX will probably be different. Connect the arduino and look to see what it is.)
This can easily be redirected to a file:
cat /dev/tty.usbmodemfa141 >log.txt
If you want an interactive session (you uploaded a sketch to make your arduino do something in response to stuff you type over the serial link):
screen /dev/tty.usbmodemfa141 9600
(9600 is the default baud rate.)