bash cli script bootstrap example, including coloured output, error handling, argument acception

bash-bootstrap-example.sh

#!/usr/bin/env bash

ColorOff='\033[0m' # Text Reset
Yellow='\033[0;33m' # Yellow for important info
Red='\033[0;31m' # Red for errors
function infoMessage() {
    echo -e ${Yellow}
    echo $1
    echo -e ${ColorOff}
}
function errMessage() {
    echo -e ${Red}
    echo $1
    echo -e ${ColorOff}
}
errHandler() {
    # Any steps that must be taken prior to exiting due to error
    errMessage "Something went wrong. Exiting now."
    exit 1
}
set -eE # -e throw ERR for any non-zero exit codes, -E as well as in any child functions
trap 'errHandler' ERR INT # Call errHandler function on ERR (non-zero exit code) or INT (ctrl-c interupt execution)

# Usage info, literally just prints this text, to be called when -h is used
show_help() {
cat << EOF
Usage: [-hyd] [-j <job name>]

This command runs the app's... something

Parameter details:
    -h display help and exit
    -y skip the confirmation
    -d dry run, don't push any changes
    -j specify the name of the job
EOF
}

# Initialise variables
OPTIND=1 # Reset for previous uses of getops in shell
OPTSTRING="hydj:" # colon after character to tell getopts that we're expecting a value. No colon chars are just flags

# Location of this file
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
cd "$DIR/.." # Go to project root, assuming your script is in a bin/ directory. You may need to adjust this line

while getopts "$OPTSTRING" opt; do
    case "$opt" in
    h)
        show_help
        exit 0
        ;;
    y)
        CONFIRMED=TRUE
        ;;
    d)
        DRY=TRUE
        infoMessage "Running dry, wow this really stands out in yellow"
        ;;
    j)
        job="$OPTARG"
        ;;
    *)
        show_help >&2
        exit 1
        ;;
    esac
done

if [[ $OPTIND == 1 ]] && [[ $@ != "" ]]; then
    echo "Arguments were passed that getopts didn't detect"
    exit 1
fi

# Example of how to check for a flag, in this case it's -y aka $CONFIRMED
if [ -z "$CONFIRMED" ]; then
    echo "-y flag was not set, $CONFIRMED is empty"
else
    echo "-y flag was set, $CONFIRMED is not empty"
fi

if [ -n "$DRY" ]; then
    echo "-d flag was set, $DRY is not empty"
else
    echo "-d flag was not set, $DRY is empty"
fi