Conditional Dates Generator

date.sh

#!/bin/bash

TEST_LIST=()
FORMAT_LIST=()

IFS=""
while :; do
	read -p "Test: " TEST
	[ -z "$TEST" ] && break;

	read -p "Format: " FORMAT
	[ -z "$FORMAT" ] && break;

	TEST_LIST+=("$TEST")
	FORMAT_LIST+=("$FORMAT")
done

read -p "Default format: " DEF_FORMAT

FORMAT_LIST+=("$DEF_FORMAT")

TEST_INDEX=0
FORMAT_INDEX=0

STRING="%[${FORMAT_LIST[FORMAT_INDEX]}]"
: $((FORMAT_INDEX++))

while :; do
	T="${TEST_LIST[TEST_INDEX]}"
	F="${FORMAT_LIST[FORMAT_INDEX]}"

	[ -n "$T" ] || break
	[ -n "$F" ] || break

	STRING="%<[$T?$STRING&%[$F]>"
	: $((TEST_INDEX++))
	: $((FORMAT_INDEX++))
done

echo
echo "index_format:"
echo -e "\t$STRING"
echo

Generate index_format strings for the Conditional Dates feature for NeoMutt.

Test can be an optional number followed by a letter: (y)ears, (m)onths, (w)eeks, (d)ays, (H)ours, (M)inutes.
The format string is compatible with strftime(3), e.g. "%d-%m-%Y" for "DD-MM-YYYY".
Enter an empty string to finish.

Example run:

$ ./date.sh
Test: d
Format: %H:%M 
Test: m
Format: %a %d 
Test: y
Format: %b %d
Test: 
Default format: %m/%y 

index_format:
    %<[y?%<[m?%<[d?%[%H:%M ]&%[%a %d]>&%[%b %d]>&%[%m/%y ]>