cal (command)
{{Short description|Shell command in various operating systems}}
{{lowercase title}}
{{Infobox software
| name = cal
| logo =
| screenshot = Cal screenshot.png
| screenshot size =
| caption = The cal command as shown in a Linux zsh session in Arch Linux
| developer = Charles Dye
| released = {{Start date and age|1971|11|3}}
| latest release version =
| latest release date =
| programming language = Plan 9: C
FreeDOS: x86 assembly language
| operating system = Unix, Unix-like, Plan 9, Inferno, MSX-DOS, FreeDOS
| platform = Cross-platform
| genre = Command
| license = util-linux: BSD-4-Clause
FreeDOS: Freeware / Source-available software
Plan 9: MIT License
| website =
}}
{{code|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.{{Cite web|url=https://archive.org/details/MSXDOS2TOOLS|title=MSX-DOS2 Tools User's Manual - MSX-DOS2 TOOLS ユーザーズマニュアル|date=April 1, 1993|via=Internet Archive}} 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.{{Cite web|url=https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/cal.html|title=ibiblio.org FreeDOS Package -- cal (Unix-like)|website=www.ibiblio.org}}
Examples
$ cal
February 2024
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
$ 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 6 2023
June 2023
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
Quirks (1752)
{{more|Calendar (New Style) Act 1750}}
$ 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."{{Cite web|url=https://docs.oracle.com/cd/E26502_01/html/E29030/cal-1.html#scrolltoc|title=Synopsis - man pages section 1: User Commands|website=docs.oracle.com}} The Plan 9 from Bell Labs manual states: "Try {{mono|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.{{Cite book |last=Thompson |first=K. |url=http://squoze.net/UNIX/v1man/man6/cal |title=Unix Programmer's Manual |last2=Ritchie |first2=D. M. |publisher=Bell Telephone Laboratories |year=1971 |edition=First |pages=cal (VI)}}
See also
- Cron – process for scheduling jobs to run on a particular date
- List of Unix commands
References
{{Reflist}}
{{Refbegin}}
- {{man|cu|cal|SUS|print a calendar}}
{{Refend}}
Sources
- {{cite book |last1=Ray |first1=Deborah S. |last2=Ray |first2=Eric J. |date=2010 |editor-last=Gulick|editor-first=Rebecca |title=Unix and Linux: Visual QuickStart Guide |publisher=Book Publishers |pages=276–278 |chapter=Calendaring with cal|chapter-url=https://books.google.com/books?id=M-z1SWdCKkwC&dq=cal+linux&pg=PA276 |isbn= 9780132104470|name-list-style=}}
External links
{{Wikibooks|Guide to Unix|Commands}}
- {{man|1|cal|Plan 9}}
- {{man|1|cal|Inferno}}
- {{man|1|cal|die.net}}
- {{man|1|cal|FreeBSD}}
- {{man|1|cal|NetBSD}}
- {{man|1|cal|OpenBSD}}
- [https://web.archive.org/web/20160221144829/http://www.csd.uwo.ca/staff/magi/personal/humour/Computer_Audience/'cal%209%201752'%20explained.html Source of explanation of cal 9 1752 phenomena] (humor)
{{Unix commands}}
{{Plan 9 commands}}
{{Calendaring software}}