Re: Curious case of arithmetic expansion

[Pierre Gaston]

On Sun, Apr 23, 2017 at 1:12 PM, Florian Mayer <mayerflorian@me.com> wrote:

Consider

$ foo=bar; bar=moo; moo=123
$ echo $foo $bar $moo
=> bar moo 123
$ echo $((foo))
=> 123
$ echo $foo $bar $moo
=> bar moo 123
$ # so far so good but
$ ((foo++))
$ echo $foo $bar $moo
=> 123 moo 123

Now my chain of indirections is broken…

It prints "124 moo 123" no?

It's because it's not really indirection, rather the content of the variable is evaluated:

$ foo=1+2;echo $((foo))
3

In the last case it evaluates the value of foo, 123, and then increment the value of foo and foo becomes 124