带有“${sta}~${stp}!d”的 Grep 命令

Question

我遇到了以下代码。 "${sta}~${stp}!d" 应该做什么？

grep --null -r -l "${isufx[@]}" -e "$ptrn" -- "${fdir[@]}" |
  sed -z "${sta}~${stp}!d"

Answer 1

来自https://www.gnu.org/software/sed/manual/sed.html#Numeric-Addresses：

first~step

This GNU extension matches every stepth line starting with line first.