Cal (Unix)

cal
	The cal command as shown in a Linux Bash session in Windows 10
Developer(s)	Charles Dye
Initial release	November 3, 1971; 52 years ago
Operating system	Unix, Unix-like, Plan 9, Inferno, MSX-DOS, FreeDOS
Platform	Cross-platform
Type	Command

cal is a standard program on Unix and Unix-like operating systems that prints an ASCII calendar of the given month or year. If the user does not specify any command-line options, cal will print a calendar of the current month.

Implementations

The cal command was present in 1st Edition Unix.

A cal command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.^[1] It is also available for FreeDOS.^[2]

Examples

$ cal
      March 1984                    
 Su Mo Tu We Th Fr Sa
              1  2  3
  4  5  6  7  8  9 10
 11 12 13 14 15 16 17
 18 19 20 21 22 23 24
 25 26 27 28 29 30 31

$ cal -3 (shows the previous, current and next month)
     March 2021            April 2021             May 2021        
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  
    1  2  3  4  5  6               1  2  3                     1  
 7  8  9 10 11 12 13   4  5  6  7  8  9 10   2  3  4  5  6  7  8  
14 15 16 17 18 19 20  11 12 13 14 15 16 17   9 10 11 12 13 14 15  
21 22 23 24 25 26 27  18 19 20 21 22 23 24  16 17 18 19 20 21 22  
28 29 30 31           25 26 27 28 29 30     23 24 25 26 27 28 29  
                                            30 31

$ cal 2021
                            2021
      January               February               March          
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  
                1  2      1  2  3  4  5  6      1  2  3  4  5  6  
 3  4  5  6  7  8  9   7  8  9 10 11 12 13   7  8  9 10 11 12 13  
10 11 12 13 14 15 16  14 15 16 17 18 19 20  14 15 16 17 18 19 20  
17 18 19 20 21 22 23  21 22 23 24 25 26 27  21 22 23 24 25 26 27  
24 25 26 27 28 29 30  28                    28 29 30 31           
31                                                                

       April                  May                   June          
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  
             1  2  3                     1         1  2  3  4  5  
 4  5  6  7  8  9 10   2  3  4  5  6  7  8   6  7  8  9 10 11 12  
11 12 13 14 15 16 17   9 10 11 12 13 14 15  13 14 15 16 17 18 19  
18 19 20 21 22 23 24  16 17 18 19 20 21 22  20 21 22 23 24 25 26  
25 26 27 28 29 30     23 24 25 26 27 28 29  27 28 29 30           
                      30 31                                       

        July                 August              September        
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  
             1  2  3   1  2  3  4  5  6  7            1  2  3  4  
 4  5  6  7  8  9 10   8  9 10 11 12 13 14   5  6  7  8  9 10 11  
11 12 13 14 15 16 17  15 16 17 18 19 20 21  12 13 14 15 16 17 18  
18 19 20 21 22 23 24  22 23 24 25 26 27 28  19 20 21 22 23 24 25  
25 26 27 28 29 30 31  29 30 31              26 27 28 29 30        
                                                                  

      October               November              December        
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  
                1  2      1  2  3  4  5  6            1  2  3  4  
 3  4  5  6  7  8  9   7  8  9 10 11 12 13   5  6  7  8  9 10 11  
10 11 12 13 14 15 16  14 15 16 17 18 19 20  12 13 14 15 16 17 18  
17 18 19 20 21 22 23  21 22 23 24 25 26 27  19 20 21 22 23 24 25  
24 25 26 27 28 29 30  28 29 30              26 27 28 29 30 31     
31

$ cal 5 2014
      May 2014        
Su Mo Tu We Th Fr Sa  
             1  2  3  
 4  5  6  7  8  9 10  
11 12 13 14 15 16 17  
18 19 20 21 22 23 24  
25 26 27 28 29 30 31

Quirks (1752)

$ cal 9 1752
  September 1752
 S  M Tu  W Th  F  S
       1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

The Gregorian calendar reform was adopted by the Kingdom of Great Britain, including its possessions in North America (later to become eastern USA and Canada), in September 1752. As a result, the September 1752 cal shows the adjusted days missing. This month was the official (British) adoption of the Gregorian calendar from the previously used Julian calendar. This has been documented in the man pages for Sun Solaris as follows. "An unusual calendar is printed for September 1752. That is the month when 11 days were skipped to make up for lack of leap year adjustments."^[3] The Plan 9 from Bell Labs manual states: "Try cal sep 1752." Date of adoption of the reform differs widely between countries so, for some users, this feature may be a bug.

References

↑ "MSX-DOS2 Tools User's Manual - MSX-DOS2 TOOLS ユーザーズマニュアル". April 1, 1993. http://archive.org/details/MSXDOS2TOOLS.
↑ "ibiblio.org FreeDOS Package -- cal (Unix-like)". https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/cal.html.
↑ "Synopsis - man pages section 1: User Commands". https://docs.oracle.com/cd/E26502_01/html/E29030/cal-1.html#scrolltoc.

cal: print a calendar – Commands & Utilities Reference, The Single UNIX Specification, Issue 7 from The Open Group

External links

cal(1) – Plan 9 Programmer's Manual, Volume 1
cal(1) – Inferno General commands Manual
cal(1) – Linux User Commands Manual
cal(1) – FreeBSD General Commands Manual
cal(1) – NetBSD General Commands Manual
cal(1) – OpenBSD General Commands Manual
Source of explanation of cal 9 1752 phenomena (humor)

0.00

(0 votes)

[1] "MSX-DOS2 Tools User's Manual - MSX-DOS2 TOOLS ユーザーズマニュアル". April 1, 1993. http://archive.org/details/MSXDOS2TOOLS.

[2] "ibiblio.org FreeDOS Package -- cal (Unix-like)". https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/cal.html.

[3] "Synopsis - man pages section 1: User Commands". https://docs.oracle.com/cd/E26502_01/html/E29030/cal-1.html#scrolltoc.

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