https://github.com/supernova106/bash-firefighter

Curated list of useful bash techniques
https://github.com/supernova106/bash-firefighter

bash yaml yaml-parser

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Curated list of useful bash techniques

• Host: GitHub
• URL: https://github.com/supernova106/bash-firefighter
• Owner: supernova106
• License: apache-2.0
• Created: 2020-03-20T18:14:03.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2022-05-11T06:13:49.000Z (about 4 years ago)
• Last Synced: 2025-07-01T01:05:34.209Z (12 months ago)
• Topics: bash, yaml, yaml-parser
• Language: Shell
• Size: 62.5 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# bash-firefighter

Curated list of useful bash techniques

## Table of Contents

- [Helper](#user-content-helper)

- [Generic](#user-content-generic)

- [Programming](#user-content-programming)

  - [Array](#user-content-array)

  - [Join](#user-content-join-method)

  - [Variables](#user-content-variables)

  - [Split](#user-content-split-method)

  - [Regex](#user-content-regex)

  - [Modules](#user-content-modules)

  - [Function in Function](#user-content-function-in-function)

- [Config Files](#user-content-config-files)

  - [Convert YAML to key=value](#user-content-yaml)

- [Cloud Provider](#user-content-cloud-provider)

  - [AWS](#user-content-aws)

## Helper

- yq, refer to [install_yq.sh](./scripts/install_yq.sh). Or [other ways](https://mikefarah.gitbook.io/yq/#on-ubuntu-16-04-or-higher-from-debian-package)

- jq, refer to [install_jq.sh](./scripts/install_jq.sh)

- Get local directory of script [local_dir.sh](./scripts/local_dir.sh)

- Get OS platform [get_os.sh](./scripts/get_os.sh)

- Promote AWS ECR Image [promote_ecr.sh](./scripts/promote_ecr.sh)

## Generic

### Check if a port is open

```sh

if [ "$(timeout 1 bash -c 'Exit on error

```sh

#!/bin/bash

set -e

```

### Retry on error

- Refer to [retry.sh](./scripts/retry.sh)

### User Continue

- Refer to [user_continue.sh](./scripts/user_continue.sh)

## Programming

### Array

Loop through indices, values

```sh

for i in "${!foo[@]}"; do

  echo "${i}: ${foo[$i]}"

done

```

Loop through values

```sh

for i in "${foo[@]}"; do

  echo "${i}"

done

```

### Join method

Join array to string

```sh

foo_arr=['a','b','c']

bar=$(IFS=. ; echo "${foo_arr[*]}")

# a.b.c

```

### Variables

Declare local variable

```sh

function foo() {

  local bar=""

}

foo

# only work with function

```

Declare global variable

```sh

bar=""

function foo() {

  echo "${bar}"

}

```

Default value

```sh

bar="${1:-default}"

echo "${bar}"

# default

```

### Split method

Split string to array

```sh

IFS='.' read -ra arr <<< "a.b.c"

echo "${arr[@]}

# ['a', 'b', 'c']

```

### Regex

Validate IP address

```sh

if [[ ! $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then

  echo -e "error! $ip is not valid"

  return 1

fi

```

### Function in Function

```sh

foo() (

  bar() {

    echo "hello"

  }

  bar

)

```

### Modules

inlude bash file as a module

```sh

.

├── foo.sh

└── modules

    └── utils.sh

$ cat modules/utils.sh

#!/bin/bash

function bar() {

  echo "hello"

}

$ cat foo.sh

#!/bin/bash

source modules/utils.sh

bar

```

## Config Files

### Yaml

Convert `yaml` file (work with up to level 2 of keys) to `key=value` environment variables file

- Detect if the input file's content changes with `md5()` hash

- allow bash to work with yaml for configuration automation

Requirements

- yq

- jq

Refer to [convert_yaml_to_env.sh](./scripts/convert_yaml_to_env.sh)

## Cloud Provider

### AWS

Getting VPC CIDR from VPC_ID

```sh

vpc_id=${1}

aws ec2 describe-vpcs --vpc-ids $vpc_id | jq -r .Vpcs[0].CidrBlock

```

Getting available ENIs ID

```sh

aws ec2 describe-network-interfaces --region us-west-2 --filters Name=status,Values=available,Name=group-name,Values= --max-items 2 | jq -r .NetworkInterfaces[].NetworkInterfaceId

```