Software & Apps Linux Learn the Linux Command: cal Display a calendar within your shell session By Juergen Haas Writer Former Lifewire writer Juergen Haas is a software developer, data scientist, and a fan of the Linux operating system. our editorial process Juergen Haas Updated March 16, 2020 Linux Switching from Windows Tweet Share Email The Linux cal program displays a simple calendar. If arguments are not specified, the current month is displayed. Synopsis The command takes the following form: cal [-smjy13 ] [[ month ] year ] Options Specify switches to modify the command output: -1: Display a single month output. This is the default.-3: Display previous, current, and next month output.-s: Display Sunday as the first day of the week. This is the default.-m: Display Monday as the first day of the week.-j: Display Julian dates (days are one-based, numbered from January 1).-y: Display a calendar for the current year. Usage Notes A single parameter specifies the year (1 through 9999) to be displayed. The year must be fully specified: cal 89 will not display a calendar for 1989. Two parameters denote the month (1 through 12) and year. If no parameters are specified, the current month's calendar is displayed. A year starts on January 1. The Gregorian Reformation is assumed to have occurred on September 3, 1752. By this time, most countries had recognized the reformation (although a few did not recognize it until the early 1900s.) Ten days following that date were eliminated by the reformation, so the calendar for that month is a bit unusual.