如果你有python 2和PyYAML，你可以使用我写的这个解析器parse_yaml.py。它做的一些更整洁的事情是让您选择一个前缀(以防您有多个具有类似变量的文件)，并从yaml文件中选择一个值。

例如，如果你有这些yaml文件:

staging.yaml:

db:
    type: sqllite
    host: 127.0.0.1
    user: dev
    password: password123

prod.yaml:

db:
    type: postgres
    host: 10.0.50.100
    user: postgres
    password: password123

您可以加载两者而不会产生冲突。

$ eval $(python parse_yaml.py prod.yaml --prefix prod --cap)
$ eval $(python parse_yaml.py staging.yaml --prefix stg --cap)
$ echo $PROD_DB_HOST
10.0.50.100
$ echo $STG_DB_HOST
127.0.0.1

甚至可以选择你想要的值。

$ prod_user=$(python parse_yaml.py prod.yaml --get db_user)
$ prod_port=$(python parse_yaml.py prod.yaml --get db_port --default 5432)
$ echo prod_user
postgres
$ echo prod_port
5432

下面是一个bash-only解析器，利用sed和awk来解析简单的yaml文件:

function parse_yaml {
   local prefix=$2
   local s='[[:space:]]*' w='[a-zA-Z0-9_]*' fs=$(echo @|tr @ '\034')
   sed -ne "s|^\($s\):|\1|" \
        -e "s|^\($s\)\($w\)$s:$s[\"']\(.*\)[\"']$s\$|\1$fs\2$fs\3|p" \
        -e "s|^\($s\)\($w\)$s:$s\(.*\)$s\$|\1$fs\2$fs\3|p"  $1 |
   awk -F$fs '{
      indent = length($1)/2;
      vname[indent] = $2;
      for (i in vname) {if (i > indent) {delete vname[i]}}
      if (length($3) > 0) {
         vn=""; for (i=0; i<indent; i++) {vn=(vn)(vname[i])("_")}
         printf("%s%s%s=\"%s\"\n", "'$prefix'",vn, $2, $3);
      }
   }'
}

它可以理解以下文件:

## global definitions
global:
  debug: yes
  verbose: no
  debugging:
    detailed: no
    header: "debugging started"

## output
output:
   file: "yes"

在解析时使用:

parse_yaml sample.yml

将输出:

global_debug="yes"
global_verbose="no"
global_debugging_detailed="no"
global_debugging_header="debugging started"
output_file="yes"

它也理解由ruby生成的yaml文件，其中可能包含ruby符号，例如:

---
:global:
  :debug: 'yes'
  :verbose: 'no'
  :debugging:
    :detailed: 'no'
    :header: debugging started
  :output: 'yes'

并将输出与前一个示例相同的结果。

脚本中的典型用法是:

eval $(parse_yaml sample.yml)

Parse_yaml接受一个前缀参数，这样导入的所有设置都有一个公共前缀(这将减少名称空间冲突的风险)。

parse_yaml sample.yml "CONF_"

收益率:

CONF_global_debug="yes"
CONF_global_verbose="no"
CONF_global_debugging_detailed="no"
CONF_global_debugging_header="debugging started"
CONF_output_file="yes"

注意，之前文件中的设置可以被后面的设置引用:

## global definitions
global:
  debug: yes
  verbose: no
  debugging:
    detailed: no
    header: "debugging started"

## output
output:
   debug: $global_debug

另一个很好的用法是先解析默认文件，然后解析用户设置，这是可行的，因为后一个设置会覆盖第一个设置:

eval $(parse_yaml defaults.yml)
eval $(parse_yaml project.yml)

如果您知道您感兴趣的标记和您期望的yaml结构，那么在Bash中编写一个简单的yaml解析器并不难。

在下面的示例中，解析器将一个结构化YAML文件读入环境变量、数组和关联数组。

注意:这个解析器的复杂性与YAML文件的结构有关。对于YAML文件的每个结构化组件，都需要一个单独的子例程。高度结构化的YAML文件可能需要更复杂的方法，例如通用的递归下降解析器。

圣诞节。yaml文件:

# Xmas YAML example
---
 # Values
 pear-tree: partridge
 turtle-doves: 2.718
 french-hens: 3

 # Array
 calling-birds:
   - huey
   - dewey
   - louie
   - fred

 # Structure
 xmas-fifth-day:
   calling-birds: four
   french-hens: 3
   golden-rings: 5
   partridges:
     count: 1
     location: "a pear tree"
   turtle-doves: two

解析器使用mapfile将文件作为数组读入内存，然后循环遍历每个标记并创建环境变量。

梨树、斑鸠和法国母鸡:最终成为简单的环境变量 呼叫鸟:变成一个数组 xmas-fifth-day:结构被表示为一个关联数组，但是如果您没有使用Bash 4.0或更高版本，您可以将这些数组编码为环境变量。 注释和空白将被忽略。

#!/bin/bash
# -------------------------------------------------------------------
# A simple parser for the xmas.yaml file
# -------------------------------------------------------------------
# 
# xmas.yaml tags
#  #                        - Ignored
#                           - Blank lines are ignored
#  ---                      - Initialiser for days-of-xmas 
#   pear-tree: partridge    - a string
#   turtle-doves: 2.718     - a string, no float type in Bash
#   french-hens: 3          - a number
#   calling-birds:          - an array of strings
#     - huey                - calling-birds[0]
#     - dewey
#     - louie
#     - fred
#   xmas-fifth-day:         - an associative array
#     calling-birds: four   - a string
#     french-hens: 3        - a number
#     golden-rings: 5       - a number
#     partridges:           - changes the key to partridges.xxx
#       count: 1            - a number
#       location: "a pear tree" - a string
#     turtle-doves: two     - a string
# 
# This requires the following routines
# ParseXMAS
#   parses #, ---, blank line
#   unexpected tag error
#   calls days-of-xmas
#
# days-of-xmas
#   parses pear-tree, turtle-doves, french-hens
#   calls calling-birds
#   calls xmas-fifth-day
# 
# calling-birds
#   elements of the array
#
# xmas-fifth-day
#   parses calling-birds, french-hens, golden-rings, turtle-doves
#   calls partridges
# 
# partridges
#   parses partridges.count, partridges.location
#

function ParseXMAS()
{

  # days-of-xmas
  #   parses pear-tree, turtle-doves, french-hens
  #   calls calling-birds
  #   calls xmas-fifth-day
  # 
  function days-of-xmas()
  {
    unset PearTree TurtleDoves FrenchHens

    while [ $CURRENT_ROW -lt $ROWS ]
    do
      LINE=( ${CONFIG[${CURRENT_ROW}]} )
      TAG=${LINE[0]}
      unset LINE[0]

      VALUE="${LINE[*]}"

      echo "  days-of-xmas[${CURRENT_ROW}] ${TAG}=${VALUE}"

      if [ "$TAG" = "pear-tree:" ]
      then
        declare -g PearTree=$VALUE
      elif [ "$TAG" = "turtle-doves:" ]
      then
        declare -g TurtleDoves=$VALUE
      elif [ "$TAG" = "french-hens:" ]
      then
        declare -g FrenchHens=$VALUE
      elif [ "$TAG" = "calling-birds:" ]
      then
        let CURRENT_ROW=$(($CURRENT_ROW + 1))
        calling-birds
        continue
      elif [ "$TAG" = "xmas-fifth-day:" ]
      then
        let CURRENT_ROW=$(($CURRENT_ROW + 1))
        xmas-fifth-day
        continue
      elif [ -z "$TAG" ] || [ "$TAG" = "#" ]
      then
        # Ignore comments and blank lines
        true
      else
        # time to bug out
        break
      fi

      let CURRENT_ROW=$(($CURRENT_ROW + 1))
    done
  }

  # calling-birds
  #   elements of the array
  function calling-birds()
  {
    unset CallingBirds

    declare -ag CallingBirds

    while [ $CURRENT_ROW -lt $ROWS ]
    do
      LINE=( ${CONFIG[${CURRENT_ROW}]} )
      TAG=${LINE[0]}
      unset LINE[0]

      VALUE="${LINE[*]}"

      echo "    calling-birds[${CURRENT_ROW}] ${TAG}=${VALUE}"

      if [ "$TAG" = "-" ]
      then
        CallingBirds[${#CallingBirds[*]}]=$VALUE
      elif [ -z "$TAG" ] || [ "$TAG" = "#" ]
      then
        # Ignore comments and blank lines
        true
      else
        # time to bug out
        break
      fi

      let CURRENT_ROW=$(($CURRENT_ROW + 1))
    done
  }

  # xmas-fifth-day
  #   parses calling-birds, french-hens, golden-rings, turtle-doves
  #   calls fifth-day-partridges
  # 
  function xmas-fifth-day()
  {
    unset XmasFifthDay

    declare -Ag XmasFifthDay

    while [ $CURRENT_ROW -lt $ROWS ]
    do
      LINE=( ${CONFIG[${CURRENT_ROW}]} )
      TAG=${LINE[0]}
      unset LINE[0]

      VALUE="${LINE[*]}"

      echo "    xmas-fifth-day[${CURRENT_ROW}] ${TAG}=${VALUE}"

      if [ "$TAG" = "calling-birds:" ]
      then
        XmasFifthDay[CallingBirds]=$VALUE
      elif [ "$TAG" = "french-hens:" ]
      then
        XmasFifthDay[FrenchHens]=$VALUE
      elif [ "$TAG" = "golden-rings:" ]
      then
        XmasFifthDay[GOLDEN-RINGS]=$VALUE
      elif [ "$TAG" = "turtle-doves:" ]
      then
        XmasFifthDay[TurtleDoves]=$VALUE
      elif [ "$TAG" = "partridges:" ]
      then
        let CURRENT_ROW=$(($CURRENT_ROW + 1))
        partridges
        continue
      elif [ -z "$TAG" ] || [ "$TAG" = "#" ]
      then
        # Ignore comments and blank lines
        true
      else
        # time to bug out
        break
      fi
 
      let CURRENT_ROW=$(($CURRENT_ROW + 1))
    done
  }

  function partridges()
  {
    while [ $CURRENT_ROW -lt $ROWS ]
    do
      LINE=( ${CONFIG[${CURRENT_ROW}]} )
      TAG=${LINE[0]}
      unset LINE[0]

      VALUE="${LINE[*]}"

      echo "      partridges[${CURRENT_ROW}] ${TAG}=${VALUE}"

      if [ "$TAG" = "count:" ]
      then
        XmasFifthDay[PARTRIDGES.COUNT]=$VALUE
      elif [ "$TAG" = "location:" ]
      then
        XmasFifthDay[PARTRIDGES.LOCATION]=$VALUE
      elif [ -z "$TAG" ] || [ "$TAG" = "#" ]
      then
        # Ignore comments and blank lines
        true
      else
        # time to bug out
        break
      fi
 
      let CURRENT_ROW=$(($CURRENT_ROW + 1))
    done
  }

  # ===================================================================
  # Load the configuration file

  mapfile CONFIG < xmas.yaml

  let ROWS=${#CONFIG[@]}
  let CURRENT_ROW=0

  # +
  # #
  #
  # ---
  # -
  while [ $CURRENT_ROW -lt $ROWS ]
  do
    LINE=( ${CONFIG[${CURRENT_ROW}]} )
    TAG=${LINE[0]}
    unset LINE[0]

    VALUE="${LINE[*]}"

    echo "[${CURRENT_ROW}] ${TAG}=${VALUE}"

    if [ "$TAG" = "---" ]
    then
        let CURRENT_ROW=$(($CURRENT_ROW + 1))
        days-of-xmas
        continue
    elif [ -z "$TAG" ] || [ "$TAG" = "#" ]
    then
        # Ignore comments and blank lines
        true
    else
        echo "Unexpected tag at line $(($CURRENT_ROW + 1)): <${TAG}>={${VALUE}}"
        break
    fi

    let CURRENT_ROW=$(($CURRENT_ROW + 1))
  done
}

echo =========================================
ParseXMAS

echo =========================================
declare -p PearTree
declare -p TurtleDoves
declare -p FrenchHens
declare -p CallingBirds
declare -p XmasFifthDay

这将产生以下输出

=========================================
[0] #=Xmas YAML example
[1] ---=
  days-of-xmas[2] #=Values
  days-of-xmas[3] pear-tree:=partridge
  days-of-xmas[4] turtle-doves:=2.718
  days-of-xmas[5] french-hens:=3
  days-of-xmas[6] =
  days-of-xmas[7] #=Array
  days-of-xmas[8] calling-birds:=
    calling-birds[9] -=huey
    calling-birds[10] -=dewey
    calling-birds[11] -=louie
    calling-birds[12] -=fred
    calling-birds[13] =
    calling-birds[14] #=Structure
    calling-birds[15] xmas-fifth-day:=
  days-of-xmas[15] xmas-fifth-day:=
    xmas-fifth-day[16] calling-birds:=four
    xmas-fifth-day[17] french-hens:=3
    xmas-fifth-day[18] golden-rings:=5
    xmas-fifth-day[19] partridges:=
      partridges[20] count:=1
      partridges[21] location:="a pear tree"
      partridges[22] turtle-doves:=two
    xmas-fifth-day[22] turtle-doves:=two
=========================================
declare -- PearTree="partridge"
declare -- TurtleDoves="2.718"
declare -- FrenchHens="3"
declare -a CallingBirds=([0]="huey" [1]="dewey" [2]="louie" [3]="fred")
declare -A XmasFifthDay=([CallingBirds]="four" [PARTRIDGES.LOCATION]="\"a pear tree\"" [FrenchHens]="3" [GOLDEN-RINGS]="5" [PARTRIDGES.COUNT]="1" [TurtleDoves]="two" )

我曾经使用python将yaml转换为json，并在jq中进行处理。

python -c "import yaml; import json; from pathlib import Path; print(json.dumps(yaml.safe_load(Path('file.yml').read_text())))" | jq '.'

我已经用python编写了shyaml，用于从shell命令行查询YAML。

概述:

$ pip install shyaml      ## installation

示例的YAML文件(具有复杂的功能):

$ cat <<EOF > test.yaml
name: "MyName !!"
subvalue:
    how-much: 1.1
    things:
        - first
        - second
        - third
    other-things: [a, b, c]
    maintainer: "Valentin Lab"
    description: |
        Multiline description:
        Line 1
        Line 2
EOF

基本的查询:

$ cat test.yaml | shyaml get-value subvalue.maintainer
Valentin Lab

更复杂的循环查询复杂的值:

$ cat test.yaml | shyaml values-0 | \
  while read -r -d $'\0' value; do
      echo "RECEIVED: '$value'"
  done
RECEIVED: '1.1'
RECEIVED: '- first
- second
- third'
RECEIVED: '2'
RECEIVED: 'Valentin Lab'
RECEIVED: 'Multiline description:
Line 1
Line 2'

以下几个要点:

all YAML types and syntax oddities are correctly handled, as multiline, quoted strings, inline sequences... \0 padded output is available for solid multiline entry manipulation. simple dotted notation to select sub-values (ie: subvalue.maintainer is a valid key). access by index is provided to sequences (ie: subvalue.things.-1 is the last element of the subvalue.things sequence.) access to all sequence/structs elements in one go for use in bash loops. you can output whole subpart of a YAML file as ... YAML, which blend well for further manipulations with shyaml.

更多的示例和文档可以在shyaml github页面或shyaml PyPI页面上找到。

很难说，因为这取决于您希望解析器从YAML文档中提取什么。对于简单的情况，你可以使用grep、cut、awk等。对于更复杂的解析，您需要使用成熟的解析库，如Python的PyYAML或YAML::Perl。