一个 grep(或 sed 或 awk)命令，用于选择文件中特定起始行之后遵循特定模式的所有行 [英] A grep (or sed, or awk) command to select all lines that follow a specific pattern after a specific start line in a file

问题描述

在 Docker Compose 的 yml 文件中，卷在以 volumes: 行开头的部分中声明，后跟模式，例如作为 -host/dir:guest:dir.该部分以下一部分的开头结束，其名称不会一直相同，并且可以是 ports:、environment: 和网络:，等等.通常有多个 volumes: 部分，并且每个部分中的行数未知(并且在 volumes: 部分中不是恒定的).

In the yml files of Docker Compose, the volumes are declared in a section that starts with volumes: line and followed by patterns such as - host/dir:guest:dir. The sesction ends with the start of the next section, which its name would not be the same all the time, and it could be any of ports:, environment:, and networks:, among others. There is usually more than one volumes: section, and the number of lines in each of those is not known (and is not constant across the volumes: sections).

我需要从 yml 的所有 volumes: 部分中提取所有的 volume 声明(即 -host/dir:guest:dir)代码>文件.

I need to extract all the volume declarations (i.e., - host/dir:guest:dir) from all volumes: sections of a yml file.

谢谢！

示例 yml 文件:

version: '2'
services:
  service1:
    image: repo1/image1
    volumes:
      - /dir1/dir2:/dir3/dir4
      - /dir5/dir6:/dir7/dir8
    ports:
      - "80:80"
  service2:
    image: repo2/image2
    volumes:
      - /dir9/dir10:/dir11/dir12
    environment:
      - A: B

推荐答案

awk one-liner

假设您在每个卷声明中都有 /

Assuming you have / in each volume declaration

输入:

version: '2'
services:
  service1:
    image: repo1/image1
    volumes:
      - /dir1/dir2:/dir3/dir4
      - /dir5/dir6:/dir7/dir8
    ports:
      - "80:80"
  service2:
    image: repo2/image2
    volumes:
      - /dir9/dir10:/dir11/dir12
    environment:
      - A: B
    volumes:
      - /dir1/dir2:/dir3/dir4
      - /dir5/dir6:/dir7/dir8
meow:

输出:

$awk '$0!~"/"{a=0}  /volumes:/{a=1; next}a' file
      - /dir1/dir2:/dir3/dir4
      - /dir5/dir6:/dir7/dir8
      - /dir9/dir10:/dir11/dir12
      - /dir1/dir2:/dir3/dir4
      - /dir5/dir6:/dir7/dir8

$0!~"/"{a=0} :如果记录/行不包含 / 这意味着它不是卷声明；设置 a=0
<代码>/volumes:/{a=1;next} :如果该行包含 volumes: 然后设置 a=1 和 next 即跳转到下一条记录
a : 如果 a=1

$0!~"/"{a=0} : If the record/line doesn't contain / that means it's not a volume declaration ; set a=0
/volumes:/{a=1; next} : If the line contains volumes: then set a=1 and next i.e jump to next record
a : To print the records if a=1

PS :如果在您的 yml 文件中，包含 / 的标签可以紧跟在卷之后，那么这可能会失败.如果是这种情况，请使用此 awk :

PS : If in your yml file a tag containing / can come just after volumes then this can fail. If that's the case then use this awk :

$awk '$1!~"-"{a=0}  /volumes:/{a=1; next}a' file

如果第一个字段不是 -

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