bash $ {variable [*]}：2中此语法的含义是什么？

Question

I read a code of someone in bash, and he writed this line:

for f in ${variable[*]}:2

Can someone explain what is the meaning of this line? what is the scope of the values that f can get?

Answer 1

The code given is a buggy attempt to expand an array skipping the first two arguments.

A corrected version would iterate over "${variable[@]:2}" , with the quotes (and the :2 inside the braces rather than outside them), as demonstrated below:

variable=( "first argument" "second argument" "third argument" "fourth argument" "fifth argument" )
printf '%s\n' "${variable[@]:2}"

...properly emits:

third argument
fourth argument
fifth argument

---

As it's already written, the code behaves as follows (and the below is not even a worst-case scenario, wherein the string would contain globs):

variable=( "first argument" "second argument" "third argument" "fourth argument" "fifth argument" )
printf '%s\n' ${variable[*]}:2  ## THIS IS BUGGY

...emits output of:

first
argument
second
argument
third
argument
fourth
argument
fifth
argument:2

Due to the missing quotes (and the use of [*] rather than [@] ), the individual words aren't kept together; and because the :2 is outside the curly braces, it's appended to the end of the last word of the result rather than changing how the expansion behaves.