util-linux-cal/plugins/holiday_highlighter/README.md

Holiday Highlighter Plugin

Plugin for cal that adds holiday highlighting via isdayoff.ru API.

Features

• Automatic country detection from system locale
• Data caching to reduce API requests
• Multiple country support: Russia, Belarus, Kazakhstan, USA, Uzbekistan, Turkey, Latvia
• Day type data: working days, weekends, shortened days, official holidays

Building

# Build entire workspace
cargo build --release --workspace

# Plugin only
cargo build --release -p holiday_highlighter

Installation

User-local

mkdir -p ~/.local/lib/cal/plugins
cp target/release/libholiday_highlighter.so ~/.local/lib/cal/plugins/

System-wide

sudo mkdir -p /usr/lib/cal/plugins
sudo cp target/release/libholiday_highlighter.so /usr/lib/cal/plugins/

Usage

# Highlight holidays for current country
cal -H

# Year with holidays
cal -y -H

# Three months with holidays
cal -3 -H

Supported countries

Code	Country	Auto-detect locales
RU	Russia	ru_RU, ru_BY, ru_KZ, ru_UZ, ru_LV
BY	Belarus	be_BY, ru_BY
KZ	Kazakhstan	kk_KZ, ru_KZ
US	USA	en_US, en
UZ	Uzbekistan	uz_UZ, ru_UZ
TR	Turkey	tr_TR
LV	Latvia	lv_LV, ru_LV

API

The plugin uses isdayoff.ru API:

Monthly request

GET https://isdayoff.ru/api/getdata?year=2026&month=01&pre=1

Yearly request

GET https://isdayoff.ru/api/getdata?year=2026&pre=1

Parameter pre=1 includes pre-holiday shortened days information.

Data format

Each character in the response represents a day of the month:

Character	Day type	Description
0	Working	Regular working day
1	Weekend	Saturday or Sunday
2	Shortened	Pre-holiday shortened day
8	Holiday	Official public holiday

Environment variables

Variable	Description
LC_ALL	Priority locale for country detection
LC_TIME	Locale for country detection
LANG	Fallback locale for country detection