BASH VERSINFO

包含完整版本信息的数组拆分为元素，如果你只是寻找主要版本，则比 $BASH_VERSION 更方便：

~> $ for ((i=0; i<=5; i++)); do echo "BASH_VERSINFO[$i] = ${BASH_VERSINFO[$i]}"; done
BASH_VERSINFO[0] = 3
BASH_VERSINFO[1] = 2
BASH_VERSINFO[2] = 25
BASH_VERSINFO[3] = 1
BASH_VERSINFO[4] = release
BASH_VERSINFO[5] = x86_64-redhat-linux-gnu