cal Command Cheat Sheet

cal (calendar) is a standard Unix utility that displays a simple, formatted calendar in the terminal. It is useful for quick date references, checking days of the week, and scripting date-related tasks.

Synopsis

cal [options] [[month] year]

Description

cal displays a calendar for the current month by default. It can also display a specific month, a whole year, or format the output in various ways (Julian dates, Monday start, etc.).

Basic Usage

Current Month

cal

Displays calendar for the current month.

Specific Month and Year

cal 12 2025

Displays December 2025.

Specific Year

cal 2024

Displays calendar for the entire year 2024.

Command Line Options

Option	Description
`-1`, `--one`	Display single month (default)
`-3`, `--three`	Display previous, current, and next month
`-s`, `--sunday`	Display Sunday as first day of week (default in some locales)
`-m`, `--monday`	Display Monday as first day of week
`-j`, `--julian`	Display Julian dates (days 1-366)
`-y`, `--year`	Display calendar for current year
`-V`, `--version`	Display version information
`-h`, `--help`	Display help text

Advanced Formatting

Three-Month View

cal -3

Useful for planning across quarter boundaries.

Julian Dates

cal -j

Displays day of year (1-365/366). Useful for project planning and computing time spans.

Highlight Today

On many systems (util-linux version), the current day is highlighted automatically. To disable:

cal --nocolor

To force color:

cal --color=always

Practical Examples

Quick Date Check

cal

Plan Next Month

cal -m $(date -d "next month" +%m) $(date -d "next month" +%Y)

Show Fiscal Year

# Alias for fiscal year view (e.g., Oct-Sep)
alias fiscal='cal -m 10 2025; cal -m 11 2025; ...'

Create Text Calendar File

cal 2025 > calendar_2025.txt

Great for printing or ASCII art inclusion in docs.

Scripting with cal

Extract Specific Date

Find the day of week for a specific date:

cal 12 2025 | grep -C 1 25

Count Fridays in a Month

cal 12 2025 | awk '{print $6}' | grep -v "^$" | wc -l

(Column 6 is Friday in default layout)

Highlight Specific Day in Output

cal | grep --color -C 6 "$(date +%e)"

Generate Calendar for Last Month

cal $(date -d "last month" +%m) $(date -d "last month" +%Y)

Historical Context

cal is one of the oldest Unix commands (V1, 1971).

The Year 1752

Try this:

cal 9 1752

Output:

   September 1752
Su Mo Tu We Th Fr Sa
       1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

Why? The British Empire (including American colonies) switched from Julian to Gregorian calendar in September 1752, skipping 11 days. cal accurately reflects this historical fact.

Cross-Platform Differences

BSD cal (macOS)

Has -h to disable highlighting (util-linux uses --nocolor)
Layout might differ slightly

ncal (Alternative)

Available on many systems (often aliased or symlinked)
Displays calendar vertically by default
Supports Easter date calculation (-e)

ncal -M  # Monday start, vertical
ncal -e  # Show Easter date

Localisation

cal respects locale settings for month names and day abbreviations.

French Calendar

LC_TIME=fr_FR.UTF-8 cal

German Calendar with Monday Start

LC_TIME=de_DE.UTF-8 cal -m

Use Cases

Project Management

Quickly check week numbers (with ncal -w) or dates.

System Administration

"Does the log rotation scheduled for the 3rd Friday match the deployment date?"

ncal -w

(Shows week numbers)

ASCII Art / MOTD

Add a calendar to your terminal startup:

# In .bashrc
cal

Exit Status

Code	Meaning
0	Success
1	Error (invalid date)

Tips

Use -3 - It's the most useful view for context
Combine with date - For relative date calculations
Check ncal - If you prefer vertical layout or need week numbers
Mind the 1752 Gap - Just a fun trivia fact!
Use Alias - alias cal='cal -3m' (3 months, Monday start)