Cal (or fCal on SNAP) is a command line utility that will output a calendar for the desired month/year. It's simple and accurate with a few useful features.
By default, Cal will display the current year. You can provide a month and year, a month, or just a year. You can also change the number of calendars per row in your display with the -n switch. See the examples below for a more through description.
Cal also will show local holidays for many countries. It's activated via the -d switch. A list of supported countries can be found at https://date.nager.at/Country
| Option | Description |
|---|---|
| -n # | Set the number of calendars per row when displaying a year. The default is 3. |
| -D | Start in Debug Mode which will display additional debugging data. Normally not used. |
| -d | Display local county holidays in the calendar |
| -c | Clear the holiday cache on the local computer and exit. The next time they are needed they will be downloaded from the Internet |
| -v | Display the current version and copyright of the program and exit. -v will also query GitHub and display the latest release version. |
| -z | Disable colored output |
| -h or -? | Display the help page |
Parameters are the arguments provided to the program. They do not include the options above.
| Parameter | Description |
|---|---|
| Year | Display the provided year |
| Month | Display the current month in the current year |
| Month Year | Display the current month in the provided year |
| If no parameter is given, display the current year |
This is a java program that is all bundled into a single jar file. To run a jar file on the command line, simply type:
java -jar cal.jar
Please note that java must be in your path and this assumes cal.jar is in your current directory. Basic command line topics and I won't go into detail here.
| Command | Result |
|---|---|
java -jar cal.jar |
Display the current year |
java -jar cal.jar -n 4 |
Display the current year - 4 months per row |
java -jar cal.jar 9 |
Display September of the current year |
java -jar cal.jar 2022 |
Display the entire year 2022 |
java -jar cal.jar 9 2022 |
Display September of 2022 |
java -jar cal.jar -D 6 |
Display June of current year in debug mode |
java -jar cal.jar -h |
Show this help information |
I would encourage anyone with a supported Linux platform to use snap. See Snapcraft Homepage for more information. You can download, install, and keep Cal up to date automatically by installing the snap via :
sudo snap install fcal (Assuming snap is installed)
I had to call it fcal as cal was already taken.
This will install the application into a sandbox where it is separate from other applications. I do want to look at packaging it via Flatpak as well, but my understanding is that Maven is not well supported. However, I need to do more investigation.
I was able to use several web pages for sources of formulas for the program. These were very helpful and I'd like to thank their authors for taking the time to record them publicly.
Determine how to calculate the first day of a month given the month and year:
- https://www.tondering.dk/claus/cal/chrweek.php#calcdow
- http://www.cplusplus.com/forum/general/174165/
Calculate if the year provided is a leap year:
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