Bash

Bash Bible

• https://github.com/dylanaraps/pure-bash-bible - lots of useful bash scripts

Template

Great template to start with:

#!/usr/bin/env bash

set -Eeuo pipefail
trap cleanup SIGINT SIGTERM ERR EXIT

script_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd -P)

usage() {
    cat <<EOF
Usage: $(basename "${BASH_SOURCE[0]}") [-h] [-v] [-f] -p param_value arg1 [arg2...]

Script description here.

Available options:

-h, --help      Print this help and exit
-v, --verbose   Print script debug info
-f, --flag      Some flag description
-p, --param     Some param description
EOF
    exit
}

cleanup() {
    trap - SIGINT SIGTERM ERR EXIT
    # script cleanup here
}

setup_colors() {
    if [[ -t 2 ]] && [[ -z "${NO_COLOR-}" ]] && [[ "${TERM-}" != "dumb" ]]; then
        NOFORMAT='\033[0m' RED='\033[0;31m' GREEN='\033[0;32m' ORANGE='\033[0;33m' BLUE='\033[0;34m' PURPLE='\033[0;35m' CYAN='\033[0;36m' YELLOW='\033[1;33m'
    else
        NOFORMAT='' RED='' GREEN='' ORANGE='' BLUE='' PURPLE='' CYAN='' YELLOW=''
    fi
}

msg() {
    echo >&2 -e "${1-}"
}

die() {
    local msg=$1
    local code=${2-1} # default exit status 1
    msg "$msg"
    exit "$code"
}

parse_params() {
    # default values of variables set from params
    flag=0
    param=''

    while :; do
        case "${1-}" in
        -h | --help) usage ;;
        -v | --verbose) set -x ;;
        --no-color) NO_COLOR=1 ;;
        -f | --flag) flag=1 ;; # example flag
        -p | --param)          # example named parameter
            param="${2-}"
            shift
            ;;
        -?*) die "Unknown option: $1" ;;
        *) break ;;
        esac
        shift
    done

    args=("$@")

    # check required params and arguments
    [[ -z "${param-}" ]] && die "Missing required parameter: param"
    [[ ${#args[@]} -eq 0 ]] && die "Missing script arguments"

    return 0
}

parse_params "$@"
setup_colors

# script logic here

msg "${RED}Read parameters:${NOFORMAT}"
msg "- flag: ${flag}"
msg "- param: ${param}"
msg "- arguments: ${args[*]-}"