Point 2 refers to creating aliases. While bash supports aliases, they are considered deprecated in favor of shell functions. That latter are more powerful and flexible and should be preferred. The example which changes ls to ls -l can be written thus:
command ls -l
Here, the command builtin is necessary to avoid a recursive call to the new ls shell function. (In this regard, using a shell function is slightly more complicated.)
That same point also failed to mention how one would ensure that the alias (or shell function) so defined would be available to subsequent shells. Indeed, one must define them in a file, such as .bashrc, for each subsequent interactive shell to provide the same functionality.
In point 4, the author discussed a number of command line editing keys. However, it should be noted that those are the default key bindings and that "set -o vi" will enable vi command line editing bindings. As before, such a setting must be encoded in a startup file (.bashrc is again the likely place).
Point 7 fails to mention that the CDPATH must be saved in a startup file (.bashrc). Likewise, point 9's changes to PS1 will be lost unless saved in a startup file (yep, .bashrc again).
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