Read YAML file from Bash script

LICENSE

MIT License

Copyright (c) 2014 Piotr Kuczynski

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

parse_yaml.sh

#!/bin/sh
parse_yaml() {
   local prefix=$2
   local s='[[:space:]]*' w='[a-zA-Z0-9_]*' fs=$(echo @|tr @ '\034')
   sed -ne "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);
      }
   }'
}

test.sh

#!/bin/sh

# include parse_yaml function
. parse_yaml.sh

# read yaml file
eval $(parse_yaml zconfig.yml "config_")

# access yaml content
echo $config_development_database

zconfig.yml

development:
  adapter: mysql2
  encoding: utf8
  database: my_database
  username: root
  password:

The following update solves my issue ...

parse_yaml() {
  
  local prefix=$2
  local s='[[:space:]]*'
  local w='[a-zA-Z0-9_]*'
  local fs=$(echo @|tr @ '\034')
  
  sed "h;s/^[^:]*//;x;s/:.*$//;y/-/_/;G;s/\n//" $1 |
  sed -ne "s|^\($s\)\($w\)$s:$s\"\(.*\)\"$s\$|\1$fs\2$fs\3|p" \
      -e "s|^\($s\)\($w\)$s:$s\(.*\)$s\$|\1$fs\2$fs\3|p" |
  awk -F$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);
    }
  }'
}

... but I've noticed that arrays like the following doesn't work:

data-plans:
  - ./data/YourCustomObject1__c-plan.json
  - ./data/YourCustomObject2__c-plan.json

Niet is a tool that help you to extract data from json or yaml file directly in your shell/bash CLI.

$ pip install niet

Consider a yaml file named project.yaml with the following contents:

project:
   meta:
       name: project-sample

You can use niet like this:

$ PROJECT_NAME=$(niet project.yaml project.meta.name)
$ echo ${PROJECT_NAME}
project-sample

What if it was proj-ect instead of project? That's what I'm trying to solve.

UPDATE: it works!

Here's a test.yaml:

test: "test output"
my-test: "my-test output"
my-array:
  - one
  - two

And the output:

❯ niet test.yml test
test output
❯ niet test.yml my-test
my-test output
❯ niet test.yml my-array
'one' 'two'

Sweet!

@wadewegner Thanks for reply!

A new stable release of niet (1.0.0) is available and fix some bad behaviors like list handling (remove ticle).

You can install/update this by using:

$ pip install -U niet

Consider your example test.yaml:

$ cat test.yaml
# test.yaml
test: "test output"
my-test: "my-test output"
my-array:
  - one
  - two

New niet behavior with update corresponding to your commands:

$ niet test.yml test
test output
$ niet test.yml my-test
my-test output
$ niet test.yml my-array # remove ticle on items
one two
$ for el in $(niet test.yaml my-array); do echo ${el}; done
one
two

Manage niet errors more properly:

$ for el in $(niet test.yaml my-array); do echo ${el}; done
one
two
$ echo $? # exit code is now available so you can handle errors more properly
0
$ niet test.yaml element.not.found
Element not found: element.not.found
$ echo $? # error during execution
1
$ niet fake.yaml test
Yaml file not found! Abort!
$ echo $? # error during execution
1
$ # You can now deal correctly with errors

Advanced usages

$ RESULTS=$(niet test.yaml element.not.found)
$ if [ "$?" == "1" ]; then echo ${RESULTS}; else echo "it's work!"; fi
Element not found: element.not.found
$ RESULTS=$(niet test.yaml my-array)
$ if [ "$?" == "1" ]; then echo ${RESULTS}; else echo "it's work!"; fi
it's work!
$ # implement your own treatments on available results

Also you can test with samples available in niet source code:

$ git clone https://github.com/gr0und-s3ct0r/niet.git
$ cd niet
$ pipenv shell
$ python setup.py install 
$ niet tests/samples/sample.yaml project.meta.tags
example sample for testing purpose

If my .ymal file is in the subdirectory how to parse that? my makefile is in top directory and my parse_yml.sh and .ymal files are in subdirectory.

i've been using @jasperes repo with some really good success. for a bash-only method of reading, parsing yaml into variables it's been working great! thanks for the work. i'll have to try out niet as well and see how that turns out. at least in my case, i'm obsessively trying to limit other language requirements as my intention is to run this on container linux. my whole project will switch to golang soon anyway, but @jasperes solution was great for laying out the general concepts for my team. i really appreciate this thread! thanks, everyone.

This is fantastic! Thank you all who have contributed to this. It was exactly what I was looking for. I think it was mentioned above by @wadewegner, it has issues with hyphenated hash keys such as proj-ect:. wadewegner you said that your first pure bash change worked for you, but had array issues. I was unsuccessful with using your approach. And unfortunately I am not able to introduce other tooling like python packages such as niet into my project. Has anyone been able to get this working for hyphenated keys?

How could i "echo" all given variables?

Thank you very much!

Trying to use Martins modified parser from stckovrflow. Input file:

schemas:
- name: exports
  tables:
  - name: wolverine
    description: sample message here
      may overflow next line
    active_date: 2019-01-07 00:00:00
    columns:
    - name: height
      type: timestamp without time zone
    - name: strength
      type: bigint
      description: sample message here
        may overflow next line
      example: 21352352
    - name: power
      type: bigint
      description: sample message here
        may overflow next line
      example: 10001
  - name: cyclops
    description: sample message here
      may overflow next line
    active_date: 2018-12-15 00:00:00
    columns:
    - name: size
      type: datetime
      description: sample message here
        may overflow next line
      example: 2018-03-03 12:30:00
    - name: power
      type: timestamp without time zone
      description: sample message here
        may overflow next line

Parse function:

function parse_yaml {
   local prefix=$2
   local s='[[:space:]]*' w='[a-zA-Z0-9_]*' fs=$(echo @|tr @ '\034')
   sed -ne "s|,$s\]$s\$|]|" \
        -e ":1;s|^\($s\)\($w\)$s:$s\[$s\(.*\)$s,$s\(.*\)$s\]|\1\2: [\3]\n\1  - \4|;t1" \
        -e "s|^\($s\)\($w\)$s:$s\[$s\(.*\)$s\]|\1\2:\n\1  - \3|;p" $1 | \
   sed -ne "s|,$s}$s\$|}|" \
        -e ":1;s|^\($s\)-$s{$s\(.*\)$s,$s\($w\)$s:$s\(.*\)$s}|\1- {\2}\n\1  \3: \4|;t1" \
        -e    "s|^\($s\)-$s{$s\(.*\)$s}|\1-\n\1  \2|;p" | \
   sed -ne "s|^\($s\):|\1|" \
        -e "s|^\($s\)-$s[\"']\(.*\)[\"']$s\$|\1$fs$fs\2|p" \
        -e "s|^\($s\)-$s\(.*\)$s\$|\1$fs$fs\2|p" \
        -e "s|^\($s\)\($w\)$s:$s[\"']\(.*\)[\"']$s\$|\1$fs\2$fs\3|p" \
        -e "s|^\($s\)\($w\)$s:$s\(.*\)$s\$|\1$fs\2$fs\3|p" | \
   awk -F$fs '{
      indent = length($1)/2;
      vname[indent] = $2;
      for (i in vname) {if (i > indent) {delete vname[i]; idx[i]=0}}
      if(length($2)== 0){  vname[indent]= ++idx[indent] };
      if (length($3) > 0) {
         vn=""; for (i=0; i<indent; i++) { vn=(vn)(vname[i])("_")}
         printf("%s%s%s=\"%s\"\n", "'$prefix'",vn, vname[indent], $3);
      }
   }'
}

Current Output :

1="name: exports"
1_1="name: wolverine"
1_1_description="sample message here"
1_1_active_date="2019-01-07 00:00:00"
1_1_1="name: height"
1_1_1_type="timestamp without time zone"
1_1_2="name: strength"
1_1_2_type="bigint"
1_1_2_description="sample message here"
1_1_2_example="21352352"
1_1_3="name: power"
1_1_3_type="bigint"
1_1_3_description="sample message here"
1_1_3_example="10001"
1_2="name: cyclops"
1_2_description="sample message here"
1_2_active_date="2018-12-15 00:00:00"
1_2_1="name: size"
1_2_1_type="datetime"
1_2_1_description="sample message here"
1_2_1_example="2018-03-03 12:30:00"
1_2_2="name: power"
1_2_2_type="timestamp without time zone"
1_2_2_description="sample message here"

But I need to get the values in nested format csv instead of synthetic numbered markers. The idea is to populate a nested relationship from parent to child elements . Anything in the same level will be written delimited by comma like below:

Wolverine.height,"timestamp without time zone",,
Wolverine.strength,bigint,"sample message here may overflow next line",21352352
Wolverine.power,bigint,"sample message here may overflow next line",10001
Cyclops.size,datetime,"sample message here may overflow next line","2018-03-03 12:30:00"
Cyclops.power,"timestamp without time zone",something,"sample message here may overflow next line",,

How can I reformat it? Can someone help ?

Hi,
I tried to use this in Jenkins for job config parsing.
I ran successfully with Python 2.6.6 but not with Python 2.7.5
Help is really appreciated.

Ran with Python 2.6.6

• echo 'Get Job Properties'
  Get Job Properties
• /usr/bin/python -V
  Python 2.6.6
• cd /bms/webapps/jenkins/workspace/pro-group/test/yaml_parser
• . parse_yaml.sh
  ++ parse_yaml access_info.yaml accessconfig_

Ran with Python 2.7.5

• echo 'Get Job Properties'
  Get Job Properties
• /usr/bin/python -V
  Python 2.7.5
• cd /bms/webapps/jenkins/workspace/pro-group/test/yaml_parser
• . parse_yaml.sh
  /bms/webapps/jenkins/jenkins881879139786658308.sh: line 29: .: parse_yaml.sh: file not found
  Build step 'Execute shell' marked build as failure

Thank you for publishing! Helped save alot of time 👍

Hello,

niet now support eval output format so you can do things like that:

$ pip install -U niet
$ echo '{"foo-biz": "bar", "fizz": {"buzz": ["zero", "one", "two", "three"]}}' | niet -f eval .
 foo_biz="bar";fizz__buzz=( zero one two three )
$ eval $(echo '{"foo-biz": "bar", "fizz": {"buzz": ["zero", "one", "two", "three"]}}' | niet -f eval .)
$ echo ${foo_biz}
bar
$ echo ${fizz__buzz}
zero one two three
$ eval $(echo '{"foo-biz": "bar", "fizz": {"buzz": ["zero", "one", "two", "three"]}}' | niet -f eval '"foo-biz"'); echo ${foo_biz}
bar
$ echo '{"foo-biz": "bar", "fizz": {"buzz": ["zero", "one", "two", "three"]}}' | niet -f eval fizz.buzz
fizz_buzz=( zero one two three );
$ eval $(echo '{"foo-biz": "bar", "fizz": {"buzz": ["zero", "one", "two", "three"]}}' | niet -f eval fizz.buzz)
$ for el in ${fizz_buzz}; do echo $el; done
zero
one
two
three

niet work with JSON and YAML input, also you can convert each format to each other, just by using pip install -U niet.

Thank you. Can we validate that the username as below is mandatory and have value, non empty field. Right now it passed.
development:
adapter: mysql2
encoding: utf8
database: my_database
username:
if anyone tried, please share. Thanks much

https://github.com/jasperes/bash-yaml for impatient !

@pkuczynski, It's work for me as well to read the key in yaml file. Thanks for that. Do you have the script to replace the value after reading? i have to replace the each value which i reads .

Hi! What is the expected output from running test.sh? Perhaps listing an output file above would be useful.

Works great.

nice script!

Works really well, thank you!

description: sample message here
may overflow next line

I have a similar issue how could we store description variable that may overflow into the next line in the same

1_2_1_description="sample message here"
TO
1_2_1_description="sample message here may overflow next line"

Thank you!

I think python is superior in this scripting situation. why on earth anyone would use a bash script to do such a thing? python is generally pre-installed in mac and Linux.

python is so much clean and readable.

pip install pyyaml

---

import yaml

FILENAME = 'your_file.yml'

with open(FILENAME) as file:
    data:dict = yaml.full_load(file)

# data is a python dictionary

The traversal logic is super. Love it !! Sometimes its just fun to do these crazy stuff with Bash.

jq for JSON and yq for YAML
https://github.com/mikefarah/yq

Hi all! This is very interested thread. Anybody knows how to make it working where string spans several lines (through "|" pipe), example:

key1: |
   1st line
   2nd line
   3rd line
key2: |
   1st line
   2nd line
   3rd line

thanks for this.
added this to end after awk as a hack not to interpret $ interpolation (application: reading serverless.yml config into bash)

 | tr "$" "#" # don't want to interpret $

i cant figure out why its not running succesfully for me whenever i execute ./test.sh it gives me error
./test.sh
./test.sh: line 4: .: parse_yaml.sh: file not found
./test.sh: line 7: parse_yaml: command not found

has anybody else faced this issue please help

@Nigam8972 try with
. ./parse_yaml.sh
if they are in the same folder (it's what I use)

Cool, just discovered this; of course the more recent suggestions are more robust and feature-rich, but I found myself needing this on constrained (i.e. busybox, sh and no python) systems where going POSIX-sh only is the way to go.

The method here by @wadewegner (or similar) to pre-process problematic keys (but not their values) was the way to go, i.e. by using "advanced" sed hold-space etc.