mirror of
https://github.com/kvz/bash3boilerplate.git
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188 lines
6.4 KiB
Bash
Executable File
188 lines
6.4 KiB
Bash
Executable File
#!/usr/bin/env bash
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# BASH3 Boilerplate
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#
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# This file:
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# - Is a template to write better bash scripts
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# - Is delete-key friendly, in case you don't need e.g. command line option parsing
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#
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# More info:
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# - https://github.com/kvz/bash3boilerplate
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# - http://kvz.io/blog/2013/02/26/introducing-bash3boilerplate/
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#
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# Version 1.1.0
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#
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# Authors:
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# - Kevin van Zonneveld (http://kvz.io)
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#
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# Usage:
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# LOG_LEVEL=7 ./main.sh -f /tmp/x -d
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#
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# Licensed under MIT
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# Copyright (c) 2013 Kevin van Zonneveld (http://kvz.io)
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### Configuration
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#####################################################################
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# Environment variables and their defaults
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LOG_LEVEL="${LOG_LEVEL:-6}" # 7 = debug -> 0 = emergency
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# Commandline options. This defines the usage page, and is used to parse cli
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# opts & defaults from. The parsing is unforgiving so be precise in your syntax
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read -r -d '' usage <<-'EOF'
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-f [arg] Filename to process. Required.
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-t [arg] Location of tempfile. Default="/tmp/bar"
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-d Enables debug mode
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-h This page
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EOF
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# Set magic variables for current file and its directory.
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# BASH_SOURCE[0] is used so we can display the current file even if it is sourced by a parent script.
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# If you need the script that was executed, consider using $0 instead.
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__dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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__file="${__dir}/$(basename "${BASH_SOURCE[0]}")"
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### Functions
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#####################################################################
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function _fmt () {
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local color_ok="\x1b[32m"
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local color_bad="\x1b[31m"
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local color="${color_bad}"
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if [ "${1}" = "debug" ] || [ "${1}" = "info" ] || [ "${1}" = "notice" ]; then
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color="${color_ok}"
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fi
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local color_reset="\x1b[0m"
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if [[ "${TERM}" != "xterm"* ]] || [ -t 1 ]; then
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# Don't use colors on pipes or non-recognized terminals
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color=""; color_reset=""
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fi
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echo -e "$(date -u +"%Y-%m-%d %H:%M:%S UTC") ${color}$(printf "[%9s]" ${1})${color_reset}";
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}
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function emergency () { echo "$(_fmt emergency) ${@}" 1>&2 || true; exit 1; }
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function alert () { [ "${LOG_LEVEL}" -ge 1 ] && echo "$(_fmt alert) ${@}" 1>&2 || true; }
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function critical () { [ "${LOG_LEVEL}" -ge 2 ] && echo "$(_fmt critical) ${@}" 1>&2 || true; }
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function error () { [ "${LOG_LEVEL}" -ge 3 ] && echo "$(_fmt error) ${@}" 1>&2 || true; }
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function warning () { [ "${LOG_LEVEL}" -ge 4 ] && echo "$(_fmt warning) ${@}" 1>&2 || true; }
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function notice () { [ "${LOG_LEVEL}" -ge 5 ] && echo "$(_fmt notice) ${@}" 1>&2 || true; }
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function info () { [ "${LOG_LEVEL}" -ge 6 ] && echo "$(_fmt info) ${@}" 1>&2 || true; }
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function debug () { [ "${LOG_LEVEL}" -ge 7 ] && echo "$(_fmt debug) ${@}" 1>&2 || true; }
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function help () {
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echo "" 1>&2
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echo " ${@}" 1>&2
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echo "" 1>&2
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echo " ${usage}" 1>&2
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echo "" 1>&2
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exit 1
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}
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function cleanup_before_exit () {
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info "Cleaning up. Done"
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}
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trap cleanup_before_exit EXIT
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### Parse commandline options
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#####################################################################
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# Translate usage string -> getopts arguments, and set $arg_<flag> defaults
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while read line; do
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opt="$(echo "${line}" |awk '{print $1}' |sed -e 's#^-##')"
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if ! echo "${line}" |egrep '\[.*\]' >/dev/null 2>&1; then
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init="0" # it's a flag. init with 0
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else
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opt="${opt}:" # add : if opt has arg
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init="" # it has an arg. init with ""
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fi
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opts="${opts}${opt}"
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varname="arg_${opt:0:1}"
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if ! echo "${line}" |egrep '\. Default=' >/dev/null 2>&1; then
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eval "${varname}=\"${init}\""
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else
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match="$(echo "${line}" |sed 's#^.*Default=\(\)#\1#g')"
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eval "${varname}=\"${match}\""
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fi
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done <<< "${usage}"
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# Reset in case getopts has been used previously in the shell.
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OPTIND=1
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# Overwrite $arg_<flag> defaults with the actual CLI options
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while getopts "${opts}" opt; do
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line="$(echo "${usage}" |grep "\-${opt}")"
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[ "${opt}" = "?" ] && help "Invalid use of script: ${@} "
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varname="arg_${opt:0:1}"
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default="${!varname}"
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value="${OPTARG}"
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if [ -z "${OPTARG}" ] && [ "${default}" = "0" ]; then
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value="1"
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fi
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eval "${varname}=\"${value}\""
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debug "cli arg ${varname} = ($default) -> ${!varname}"
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done
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shift $((OPTIND-1))
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[ "$1" = "--" ] && shift
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### Switches (like -d for debugmode, -h for showing helppage)
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#####################################################################
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# debug mode
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if [ "${arg_d}" = "1" ]; then
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set -o xtrace
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LOG_LEVEL="7"
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fi
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# help mode
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if [ "${arg_h}" = "1" ]; then
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# Help exists with code 1
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help "Help using ${0}"
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fi
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### Validation (decide what's required for running your script and error out)
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#####################################################################
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[ -z "${arg_f}" ] && help "Setting a filename with -f is required"
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[ -z "${LOG_LEVEL}" ] && emergency "Cannot continue without LOG_LEVEL. "
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### Runtime
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#####################################################################
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# Exit on error. Append ||true if you expect an error.
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# `set` is safer than relying on a shebang like `#!/bin/bash -e` because that is neutralized
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# when someone runs your script as `bash yourscript.sh`
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set -o errexit
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set -o nounset
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# Bash will remember & return the highest exitcode in a chain of pipes.
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# This way you can catch the error in case mysqldump fails in `mysqldump |gzip`
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set -o pipefail
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if [[ "${OSTYPE}" == "darwin"* ]]; then
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info "You are on OSX"
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else
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info "You are on Linux"
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fi
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debug "Info useful to developers for debugging the application, not useful during operations."
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info "Normal operational messages - may be harvested for reporting, measuring throughput, etc. - no action required."
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notice "Events that are unusual but not error conditions - might be summarized in an email to developers or admins to spot potential problems - no immediate action required."
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warning "Warning messages, not an error, but indication that an error will occur if action is not taken, e.g. file system 85% full - each item must be resolved within a given time. This is a debug message"
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error "Non-urgent failures, these should be relayed to developers or admins; each item must be resolved within a given time."
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critical "Should be corrected immediately, but indicates failure in a primary system, an example is a loss of a backup ISP connection."
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alert "Should be corrected immediately, therefore notify staff who can fix the problem. An example would be the loss of a primary ISP connection."
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emergency "A \"panic\" condition usually affecting multiple apps/servers/sites. At this level it would usually notify all tech staff on call."
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