arrays - nullglob 和数组

Question

我可以创建一个数组，然后从这个数组中删除

$ foo=(a b c)

$ unset foo[0]

$ echo ${foo[*]}
b c

但是，如果设置了 nullglob，那么我无法从数组中删除

$ shopt -s nullglob

$ foo=(a b c)

$ unset foo[0]

$ echo ${foo[*]}
a b c

Answer 1

unset 'foo[0]'

Bash thinks the var[1] is a glob, doesn't find a file that matches it, and per instruction of nullglob removes it, causing your script to run unset instead of unset var[1] - and nothing gets unset. The correct way to fix this issue is to quote the variable name (and always specify -v explicitly): unset -v 'var[1]'.

§ nullglob