I'm reading a book, Learning Unix for OS X by Dave Taylor. It says:

To quickly see all of the binary executables—Unix programs—on your system,

Open the Terminal, hold down the Shift key, and press Esc-?, or press Control-X followed by Shift-1 (using Shift-1 to get an exclamation mark).

Before the commands are displayed in the Terminal, however, you’ll first be prompted (asked) to make a choice:

$ 
Display all 1453 possibilities? (y or n)

If you press the n key on your keyboard, you’ll be taken back to a command prompt and nothing else will happen. However, if you press the y key, you’ll see a multi-column list of Unix commands stream past in the Terminal window.

However, the problem is, when I hold down Shift key and press Esc-? nothing happens. Same for Pressing Control-X followed by Shift-1. What am I doing wrong? Is there any setting that I need to enable before using this feature? I'm using iTerm2 on Mac El Capitan. It doesn't work on the stock terminal either. Any help would be much appreciated. Thank you.