Shell Script Sample

sample.sh

#!/bin/bash

# --------------
# TIPS & TRICKS
# --------------
: '
---
- SECTION
---

Long comment section
without needed to add # at the beginning of each lines

'



#
# INIT
#

# Exit if any errros occur
[[ $PRG_PANIC_ON_ERROR == "true" ]] && set -euo pipefail;

# Activate debug mode if needed
[[ $PRG_LOGLEVEL == "debug" ]] && set -x;

# TRAPS
trap '__handle_error' ERR # Custom signal "ERR" when it is sent to stdout/stderr via echo
trap '__handle_exit' EXIT
trap '__handle_interrupt' SIGINT SIGQUIT SIGTERM
# trap '__handle_cleanup' SIGHUP


#
# GLOBALS
#

# Colors

_RESET="\033[0m"
_GREEN="\033[0;32m"
_BOLD="\033[1m"
_RED="\033[0;31m"
_YELLOW="\033[0;33m"
_GREY="\033[0;37m"


_PRG_NAME_=${PRG_NAME:-$(basename $0)}
_PRG_SHORT_DESC_="${PRG_SHORT_DESC}"

# [TODO] : Change all placeholders <...>
_PRG_EXAMPLES="EXAMPLES
  <write examples here...>
"
_PRG_NOTES="NOTES
  <write notes here...>
"
_PRG_AUTHOR_NAME="<USERNAME>"
_PRG_AUTHOR_EMAIL="<EMAIL>"
_PRG_AUTHOR_YEAR="<YYYY>"
_PRG_AUTHOR="AUTHOR
  <write author here...>
"

_PRG_LICENSE="LICENSE
MIT License - Copyright (c) [$_PRG_AUTHOR_YEAR] [$_PRG_AUTHOR_NAME<$_PRG_AUTHOR_EMAIL>]
"
# [/TODO]

#
# INCLUDES / IMPORTS
#

# source <path/to/source/file/to/load
                         
#                        
# HELPERS                
#                        
                         
function GetDatetime(){
  printf "time=%s" $(date -u +"%Y-%m-%dT%H:%M:%S.%3NZ") # RFC3339
}



function _log(){

  if test $# -gt 0; then
    local _orig_args="$*"
    local _type="${1}";shift
    local _tag="rzo/$_PRG_NAME_"
    local _prefix
    local _suffix
    local _msg="$*"

    case $_type in
      --err)
        _prefix='::'
        _color="${_RED}"
        ;;
      --step)
        _type="notice"
        _prefix='::'
        _color="${_BOLD}"
        ;;
      --done)
        _type="notice"
        _prefix=':: Done.'
        _color="${_BOLD}"
        ;;
      --task)
        _type="notice"
        _prefix='   -'
        _suffix='...'
        _color="${YELLOW}"
        ;;
      *)
        _msg="$_orig_args"
        _type="notice"
        _prefix='   ?'
        _color="${RESET}"
    esac

    if [[ $PRG_ENABLE_ENHANCED_LOGGER == "yes" ]];then
      _msg="${_prefix} $_msg $_suffix"
      logger -t $_tag -p ${_type##*-} -s "$_msg"
    else
      _msg="$(GetDatetime) ${_color}${_prefix} $_tag: $_msg $_suffix $RESET"
      echo $_msg
    fi
  fi
}


function Step() {
  echo ""
  _log --step "$*"
  
}

function Task() {
  _log --task "$*"
}

function Log() {
  if [[ $PRG_LOGLEVEL == "debug" ]]; then
    _log "$*"
  fi;
}

function Err() {
  _log --err "$*"
  exit 1
}

function Done() {
  _log --done "$*"
  echo ""
}

function Check() {
  local _code=$1
  shift
  local _message="${*}"
  if [[ $_code != 0 ]]; then
    Err "$_message"
    exit 1
  else
    Log "No errors"
  fi;
}


#
# FUNCTIONS
#

# [TODO] : Change placeholders <...>
usage(){
    cat <<USAGE
NAME
    ${_PRG_NAME_} - ${_PRG_SHORT_DESC_}

SYNOPSIS
    ${_PRG_NAME_} [OPTIONS]

OPTIONS
    -h|--help                              Show help
    -<OPT_SHORT>|--<OPT_LONG> <OPT_ARGS>   <OPT_DESC> 
USAGE
}

usage_long(){
  # print share version
  usage
  
  cat <<USAGE_EXTRAS
${_PRG_NOTES}

${_PRG_EXAMPLES}

${_PRG_AUTHOR}

${_PRG_LICENSE}

USAGE_EXTRAS
}

# [TODO] : Use this bloc to document you function
#
# <FUNC NAME> : <FUNC DESC>
# 
#   @param <var>:<type> - Desc
#   @param <var>:<type> - Desc
#
#   @return <var>:<type> - Desc
#
# [/TODO]

#
# OPTIONS
#

if test $# -eq 0
then
    usage
fi

while test $# -gt 0; do
    case "$1" in
        -h|--help)
            usage_long
            exit 0
            ;;
        -<OPT>|--<OPT_LONG>) # [TODO] : Change HERE
            shift
            _optval_<OPT>=$1 # [TODO] : Change HERE
            shift
            ;;
        *)
            e "Option [$1] is not supported!"
            usage
            exit 1
            ;;
    esac
done


#
# REQUIREMENTS
#

Step "Check requirements"
: "${<VAR>:?<VAR> is required!}" # [TODO] : Change HERE
Done

#
# PARAMS
#

_param_1=${<NAME>:-<VALUE} # [TODO] : Change HERE
... # [TODO] : Change HERE
_param_X=${<NAME>:-<DEFAULT_VALUE>} # [TODO] : Change HERE


#
# LOGIC
#

# HANDLERS

__handle_error(){
  Step "Handle Error:"
  # Logic here
  Done
}

__handle_exit(){
  Step "Handle onExit"
  # Logic here
  Done
}

__handle_interrupt(){
  Step "Handle onInterrupt: CTRL+C Hit"
  Task "Now exiting"
  # Logic here
  Done
}

#__handle_cleanup(){
#  echo __handle_cleanup
#}


# MAIN

main(){
   local _<PARAM_1>="$1" # [TODO] : Change HERE
   local _<PARAM_2>="$2" # [TODO] : Change HERE
   
   <logic here> # [TODO] : Change HERE
   
   # Done or Err
}

main $_param_1 ... $_param_X

Example: mark-as-hardened.sh

#!/bin/bash 

# 
# GLOBAL VARS
#

__PROGRAM__=$(basename $0)

#
# INITIALIZE
#

set +e 

# Exit if any errros occur
[[ $PRG_PANIC_ON_ERROR == "true" ]] && set -euo pipefail;

# Activate debug mode if needed
[[ $PRG_LOGLEVEL == "debug" ]] && set -x;


#
# IMPORTS
#

source <source.sh>

#
# VARS
#

_SAWS_VMIHS_METADATA_FILE="${SAWS_VMIHS_METADATA_FILE:-/opt/saws/vmihs/.metadata.json}"

#
# HELPERS
#


usage(){
    cat <<USAGE
Usage : ${__PROGRAM__} [OPTIONS]
    
    Mark the current instance and its AMI as hardened 

 OPTIONS:
    -h|--help               Show help
    -m|--metafile <path>    Metadata file path
USAGE
}

x:err() {                                                                                                            
    echo -e "ERROR - $*"
    exit 1                                                                                                                    
}  

function x:check() {
  local _code=$1
  shift
  local _message="${*}"
  if [[ $_code != 0 ]]; then
    x:err "$_message"
    exit 1
  else
    echo -e "Success."
  fi;
}


#
# LOGIC
#

while test $# -gt 0; do
    case "$1" in
        -h|--help)
            usage
            exit 0
            ;;
        -m|--metafile)
            shift
            _optval_metafile=$1
            shift
            ;;
        *)
            echo "Option [$1] is not supported!"
            usage
            exit 1
            ;;
    esac
done

main() {
    local _metafile="$1"
    local _instance_id_meta="$(ec2-metadata -i)"
    local _instance_id="${_instance_id_meta#*: }"

    local _instance_ami_meta="$(ec2-metadata -a)"
    local _instance_ami_id="${_instance_ami_meta#*: }"

    local _request_input_file=$(mktemp)

    if [[ -z "${_instance_id}" ]] || [[ -z "${_instance_ami_id}" ]]; then
        x:err "ERROR: Unable to get instance[${_instance_id}] and ami[${_instance_ami_id}]"
    fi

    echo -e "Attempt to mark instance[${_instance_id}] and ami[${_instance_ami_id}] as hardened"

    if [[ -z "${_metafile}" ]]; then
        echo -e "No given metafile. use default metadata file[${_SAWS_VMIHS_METADATA_FILE}]"
        _metafile="${_SAWS_VMIHS_METADATA_FILE}"
    fi

    echo -e "Ensuring metadata file[${_metafile}] exists..."
    if [[ ! -f "${_metafile}" ]]; then
        x:err "Metadata file[${_metafile}] not found."
    fi

    echo -e "Building request input file and store it at path[${_request_input_file}]..."
    jq  --arg amiId ${_instance_ami_id} --arg instanceId ${_instance_id} -r '
    {
    "DryRun": false,
    "Resources": [$amiId, $instanceId],
    "Tags": . | to_entries | map({"Key": .key, "Value": .value})
    }'  < ${_metafile} > ${_request_input_file}
    x:check $? "ERROR - Unable to create request input file."

    echo -e "Creating tags on instance[${_instance_id}] and ami[${_instance_ami_id}] from input[${_request_input_file}]..."
    aws ec2 create-tags --cli-input-json file://${_request_input_file}
    x:check $? "ERROR - Unable to create tags."

    echo -e "Cleaning up..."
    rm -rf ${_request_input_file}

    echo -e "Done."

}


main "${_optval_metafile}"

Retries

#!/bin/bash

MAX_RETRIES=5
RETRY_COUNT=0
DELAY=1

while [ $RETRY_COUNT -lt $MAX_RETRIES ]; do
    /path/to/your/script.sh
    EXIT_CODE=$?

    if [ $EXIT_CODE -eq 0 ]; then
        exit 0
    fi

    RETRY_COUNT=$((RETRY_COUNT + 1))
    sleep $DELAY
    DELAY=$((DELAY * 2))
done

exit 1

References

1. https://github.com/yaacov/argparse-sh/tree/main
2. https://medium.com/@Drew_Stokes/bash-argument-parsing-54f3b81a6a8f
3. https://github.com/andsens/docopt.sh
4. https://github.com/docopt/docopts

# Log levels:
# - 1: DEBUG
# - 2: INFO
# - 3: WARN
# - 4: ERROR