Add a quick little script to check a file's age

check_file_age

@@ -0,0 +1,170 @@
+#! /bin/bash
+#
+# check_file_age
+# Alerts if a file's age is beyond a specific threshold
+# Copyright (C) 2021 Vintage Salt <rehashedsalt@cock.li>
+#
+# Distributed under terms of the MIT license.
+#
+set -e
+
+# Read-only set-once variables
+declare -r _name="$(basename -- "$0")"
+# Options
+declare -i _optcritthresh
+declare -i _optwarnthresh
+declare -i _opthelp
+declare -i _optverbose
+# Working variables
+declare -a _args
+declare _return
+
+# Helper functions
+log() {
+	# Print a line to the terminal if _optverbose is greater than $2
+	# $2 defaults to 0
+	# loglevel 0: Daily-use messages
+	# loglevel 1: Detailed but not quite debugging
+	# loglevel 2: Definitely debugging
+	[ -z "$1" ] && return 1
+	if (( _optverbose >= ${2:-0} )); then
+		printf "%s\\n" "$1"
+	fi
+}
+warn() {
+	# Print a yellow line to the terminal, respecting _optverbose
+	[ -z "$1" ] && return 1
+	if (( _optverbose >= ${2:-0} )); then
+		if [ -t 1 ]; then
+			printf "\\e[33m%s\\e[0m\\n" "$1"
+		else
+			printf "WARN: %s\\n" "$1"
+		fi
+	fi
+}
+error() {
+	# Print a red line to the terminal, exit if $2 is specified
+	[ -z "$1" ] && return 1
+	if [ -t 2 ]; then
+		printf "\\e[31m%s\\e[0m\\n" "$1" 1>&2
+	else
+		printf "ERROR: %s\\n" "$1" 1>&2
+	fi
+	[ -z "$2" ] && return
+	exit "${2:-1}"
+}
+has() {
+	# Parse out all arguments and try to find them in path
+	# If an argument cannot be found, set _return and fail
+	for prog in "$@"; do
+		if ! command -v "$prog" > /dev/null 2>&1; then
+			_return="$prog"
+			return 1
+		fi
+	done
+	return 0
+}
+
+# Core program functions
+checkage() {
+	# Check a file's age against the values of _optwarnthres and _optcritthresh
+	file="${_args[0]}"
+	log "Checking file $file" 1
+	# Get some times
+	filetimestamp="$(stat -c %Y -- "$file")"
+	now="$(date +%s)"
+	# Get our age
+	age="$(( now - filetimestamp ))"
+	log "File is $age seconds old" 1
+	# Throw out warns and crits as necessary
+	if (( age >= _optcritthresh )); then
+		echo "CRITICAL: $file is $age seconds old (max $_optcritthresh)"
+		exit 2
+	elif (( age >= _optwarnthresh)); then
+		echo "WARNING: $file is $age seconds old (max $_optwarnthresh)"
+		exit 1
+	else
+		echo "OK: $file"
+		exit 0
+	fi
+}
+printhelp() {
+	cat << EOF
+Usage: $_name <FILE> [OPTION]...
+A Nagios monitoring plugin for checking a file's age
+
+Arguments:
+  FILE			The file to monitor
+
+Flags:
+  -c			The maximum age of the file in seconds before a CRITICAL status is
+			returned
+  -h			Print this help text
+  -v			Print more status messages. Stacks
+  -w			The maximum age of the file in seconds before a WARNING status is
+			returned
+
+Copyright (c) 2021 rehashedsalt@cock.li
+Licensed under the MIT license
+EOF
+}
+
+# Main
+main() {
+	# Parse out arguments
+	while [ -n "$1" ]; do
+		# Parse out flags
+		while getopts ":c:hvw:" opt; do
+			case $opt in
+				c)
+					_optcritthresh="$OPTARG"
+					;;
+				h)
+					_opthelp=1
+					;;
+				v)
+					_optverbose+=1
+					;;
+				w)
+					_optwarnthresh="$OPTARG"
+					;;
+				:)
+					error "Option requires argument: -$OPTARG" 2
+					;;
+				*)
+					error "Invalid option: -$OPTARG" 2
+					;;
+			esac
+		done
+		# Store arguments
+		shift $((OPTIND - 1))
+		if [ -n "$1" ]; then
+			_args+=("$1")
+			shift
+		fi
+		unset OPTIND
+	done
+	# Early hook for help
+	[ -n "$_opthelp" ] && printhelp && exit 0
+	# Validate critical options
+	if [ -z "${_args[0]}" ]; then
+		error "Must specify a file" 50
+	fi
+	if ! (( _optcritthresh > 0 )) 2>/dev/null; then
+		error "Critical threshold must be an integer greater than 0" 50
+	fi
+	if ! (( _optwarnthresh > 0 )) 2>/dev/null; then
+		error "Warning threshold must be an integer greater than 0" 50
+	fi
+	# Validate core program dependencies
+	log "Validating dependencies" 2
+	if ! has basename; then
+		error "Failed to find program: $_return" 50
+	fi
+
+	# Do the do
+	checkage
+}
+
+main "$@"
+