我正在嘗試破解一些終端程式碼

Question

-a和是什麼-G意思？謝謝。

sudo usermod -a -G www-data username

Answer 1

從man usermod：

   -a, --append
       Add the user to the supplementary group(s). Use only with the -G option.

   -G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
       A list of supplementary groups which the user is also a member of. Each group is separated from the next by a comma, with no
       intervening whitespace. The groups are subject to the same restrictions as the group given with the -g option.

       If the user is currently a member of a group which is not listed, the user will be removed from the group. This behaviour can be
       changed via the -a option, which appends the user to the current supplementary group list.

簡而言之，將用戶sudo usermod -aG www-data username新增username到www-data群組中。