As I will be deploying this script on multiple machines with the very same system Linux Mint 18 with rather same configuration, I would like to be semi-sure I won't screw things up much.

This little script will run every day from the root's crontab and will be logged into syslog or my own log AFTER this manual script passes some quality checks. Logging is not the question now. Automation is also not the question yet. In the meantime it is being executed as normal user and elevated with sudo internally. No help message needed. And no docs needed either. I ran it through Shellcheck.net. I have also ruled out the use of subjectively nicer apt, because it is not meant to be used in sctipts.

Conditions still are:

1. Code readability
2. Output readability
3. Colored headings
4. Attempt to correct things
5. Clean-up after update

My current idea is a little more advanced than the first one, having implemented exit code checking was a great idea:

#!/bin/bash


RED="\033[1;31m"
GREEN="\033[1;32m"
YELLOW="\033[1;33m"
NOCOLOR="\033[0m"


function show_success {

  echo -e "${GREEN}Success.${NOCOLOR}\n"

}


function show_error_and_exit {

  echo -e "${RED}An error occured.${NOCOLOR}\n"

  exit "$1"

}

function error_handler {

  if [[ $1 -ne 0 ]];
  then

    show_error_and_exit "$2"

  else

    show_success

  fi

}


echo -e "\n${GREEN}Step 1: configure packages${NOCOLOR}"
echo -e "${YELLOW}dpkg --configure -a${NOCOLOR}"

sudo dpkg --configure -a

error_handler $?  1


echo -e "${GREEN}Step 2: fix broken dependencies${NOCOLOR}"
echo -e "${YELLOW}apt-get install --fix-broken${NOCOLOR}"

sudo apt-get install --fix-broken

error_handler $?  2


echo -e "${GREEN}Step 3: update cache${NOCOLOR}"
echo -e "${YELLOW}apt-get update${NOCOLOR}"

sudo apt-get update

error_handler $?  3


echo -e "${GREEN}Step 4: upgrade packages${NOCOLOR}"
echo -e "${YELLOW}apt-get upgrade${NOCOLOR}"

sudo apt-get upgrade

error_handler $?  4


echo -e "${GREEN}Step 5: upgrade distribution${NOCOLOR}"
echo -e "${YELLOW}apt-get dist-upgrade${NOCOLOR}"

sudo apt-get dist-upgrade

error_handler $?  5


echo -e "${GREEN}Step 6: remove unused packages${NOCOLOR}"
echo -e "${YELLOW}apt-get --purge autoremove${NOCOLOR}"

sudo apt-get --purge autoremove

error_handler $?  6


echo -e "${GREEN}Step 7: clean up${NOCOLOR}"
echo -e "${YELLOW}apt-get autoclean${NOCOLOR}"

sudo apt-get autoclean

error_handler $?  7