What is opt-cmd-] bound to and how can I switch this off?

download this Tool GPU-Z and run it. It will read all the data of your GPU and show you your memory.

The way I see it : Dedicated Memory: 1009 MB - this is the onboard memory on the video card itself Shared Memory: 765 MB - This is system memory (plugged into motherboard) the card can use along with its own dedicated onboard ram.

The issue here is that you're using single quotes. It prevents shell from variable expansion. Use double quotes instead (and escape internal double quotes) or put additional single quotes around variable $X.

E.g. compare this command:

$ test_var="wiii" && echo '"$test_var"'
"$test_var"

and this:

$ test_var="wiiii" && echo "\"$test_var\""
"wiiii"

and this one:

$ test_var="wiiii" && echo '"'$test_var'"'
"wiiii"

Additional information to read:

• SO question
• bash-hackers wiki