若有个名为nginx的容器：

docker run -it nginx bash

修改内容后退出，使用docker commit命令提交修改。

Usage:  docker commit [OPTIONS] CONTAINER [REPOSITORY[:TAG]]

Create a new image from a container's changes

Options:
  -a, --author string    Author (e.g., "John Hannibal Smith <hannibal@a-team.com>")
  -c, --change list      Apply Dockerfile instruction to the created image
  -m, --message string   Commit message
  -p, --pause            Pause container during commit (default true)

如 :

docker commit -a "John Click" -m "add extra plugins" 2ff7f15ca033 nginx:latest

2ff7f15ca033 为刚才修改的docker容器id。