Software:cal (command)
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| Developer(s) | Charles Dye |
|---|---|
| Initial release | November 3, 1971 |
| Written in | Plan 9: C FreeDOS: x86 assembly language |
| Operating system | Unix, Unix-like, Plan 9, Inferno, MSX-DOS, FreeDOS |
| Platform | Cross-platform |
| Type | Command |
| License | util-linux: BSD-4-Clause FreeDOS: Freeware / Source-available software Plan 9: MIT License |
cal is a command-line utility on a number of computer operating systems including Unix, Plan 9, Inferno and Unix-like operating systems such as Linux 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. The command is a standard program on Unix and specified in the Single UNIX Specification.
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. This implementation only supports the Gregorian calendar (New Style) and may be distributed freely, with or without source. The FreeDOS version was developed by Charles Dye.[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)
June 2022 July 2022 August 2022
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 1 2 1 2 3 4 5 6
5 6 7 8 9 10 11 3 4 5 6 7 8 9 7 8 9 10 11 12 13
12 13 14 15 16 17 18 10 11 12 13 14 15 16 14 15 16 17 18 19 20
19 20 21 22 23 24 25 17 18 19 20 21 22 23 21 22 23 24 25 26 27
26 27 28 29 30 24 25 26 27 28 29 30 28 29 30 31
$ cal 2023
2023
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 3 4 5 6 7 1 2 3 4 1 2 3 4
8 9 10 11 12 13 14 5 6 7 8 9 10 11 5 6 7 8 9 10 11
15 16 17 18 19 20 21 12 13 14 15 16 17 18 12 13 14 15 16 17 18
22 23 24 25 26 27 28 19 20 21 22 23 24 25 19 20 21 22 23 24 25
29 30 31 26 27 28 26 27 28 29 30 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 1 2 3 4 5 6 1 2 3
2 3 4 5 6 7 8 7 8 9 10 11 12 13 4 5 6 7 8 9 10
9 10 11 12 13 14 15 14 15 16 17 18 19 20 11 12 13 14 15 16 17
16 17 18 19 20 21 22 21 22 23 24 25 26 27 18 19 20 21 22 23 24
23 24 25 26 27 28 29 28 29 30 31 25 26 27 28 29 30
30
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 1 2 3 4 5 1 2
2 3 4 5 6 7 8 6 7 8 9 10 11 12 3 4 5 6 7 8 9
9 10 11 12 13 14 15 13 14 15 16 17 18 19 10 11 12 13 14 15 16
16 17 18 19 20 21 22 20 21 22 23 24 25 26 17 18 19 20 21 22 23
23 24 25 26 27 28 29 27 28 29 30 31 24 25 26 27 28 29 30
30 31
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 3 4 5 6 7 1 2 3 4 1 2
8 9 10 11 12 13 14 5 6 7 8 9 10 11 3 4 5 6 7 8 9
15 16 17 18 19 20 21 12 13 14 15 16 17 18 10 11 12 13 14 15 16
22 23 24 25 26 27 28 19 20 21 22 23 24 25 17 18 19 20 21 22 23
29 30 31 26 27 28 29 30 24 25 26 27 28 29 30
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. Special handling of 1752 is known to have appeared as early as the first edition of the Unix Programmer's Manual in 1971.[4]
See also
- Cron – process for scheduling jobs to run on a particular date
- List of Unix commands
References
- ↑ "MSX-DOS2 Tools User's Manual - MSX-DOS2 TOOLS ユーザーズマニュアル". April 1, 1993. https://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.
- ↑ Thompson, K.; Ritchie, D. M. (1971). Unix Programmer's Manual (First ed.). Bell Telephone Laboratories. pp. cal (VI). http://squoze.net/UNIX/v1man/man6/cal.
- : print a calendar – Commands & Utilities Reference, The Single UNIX Specification, Issue 7 from The Open Group
Sources
- Ray, Deborah S.; Ray, Eric J. (2010). "Calendaring with cal". in Gulick, Rebecca. Unix and Linux: Visual QuickStart Guide. Book Publishers. pp. 276–278. ISBN 9780132104470. https://books.google.com/books?id=M-z1SWdCKkwC&dq=cal+linux&pg=PA276.
External links
- – Plan 9 Programmer's Manual, Volume 1
- – Inferno General commands Manual
- – Linux User Commands Manual
- – FreeBSD General Commands Manual
- – NetBSD General Commands Manual
- – OpenBSD General Commands Manual
- Source of explanation of cal 9 1752 phenomena (humor)
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