ticket-master.sh

#!/bin/bash

# If today is between two dates (following the YYYY-MM-DD format), then return "success" (e.g. 0).
# Else, return error (1).
time_between() {
	begin_date=$1
	end_date=$2
	today=`date '+%Y-%m-%d'`

	# Bash (usually) has no '>=' or '<=' when it comes to string comparison, so
	# we compare separately as a workaround.
	if [[ "$today" == "$begin_date" || "$today" > "$begin_date" && "$today" < "$end_date" || "$today" == "$end_date" ]]; then
		return 0
	fi

	return 1
}

# We expect the file to contain the following (separated by tabs, or set IFS=, for CSV)
# Start time (YYYY-MM-DD)        End time (YYYY-MM-DD)        Name/string to display if between those times
while read beg end name; do
	if time_between "$beg" "$end"; then
		echo $name

		# Comment this if there could possibly be more than one string to display
		exit 0
	fi
done < "$HOME/Desktop/queue-king.txt"

echo 'No one found for today.' >&2
exit 1