CAL(1POSIX)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
cal — print a calendar

SYNOPSIS

cal [[month] year]

DESCRIPTION
The cal utility shall write a calendar to standard output using the Julian calendar for dates from January 1, 1 through September 2, 1752 and the Gregorian calendar for dates from September 14, 1752 through December 31, 9999 as though the Gregorian calendar had been adopted on September 14, 1752.

If no operands are given, cal shall produce a one-month calendar for the current month in the current year. If only the year operand is given, cal shall produce a calendar for all twelve months in the given calendar year. If both month and year operands are given, cal shall produce a one-month calendar for the given month in the given year.

OPTIONS
None.

OPERANDS
The following operands shall be supported:

month
    Specify the month to be displayed, represented as a decimal integer from 1 (January) to 12 (December).

year
    Specify the year for which the calendar is displayed, represented as a decimal integer from 1 to 9999.

STDIN
Not used.

INPUT FILES
None.

ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of cal:

LANG
    Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1-2017, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)

LC_ALL
    If set to a non-empty string value, override the values of all the other internationalization variables.

LC_CTYPE
    Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments).

LC_MESSAGES
    Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error, and informative messages written to standard output.

LC_TIME
    Determine the format and contents of the calendar.

NLSPATH
    Determine the location of message catalogs for the processing of LC_MESSAGES.

TZ  Determine the timezone used to calculate the value of the current month.

ASYNCHRONOUS EVENTS
Default.

STDOUT
The standard output shall be used to display the calendar, in an unspecified format.

STDERR
The standard error shall be used only for diagnostic messages.

OUTPUT FILES
None.

EXTENDED DESCRIPTION
None.

EXIT STATUS
The following exit values shall be returned:

0   Successful completion.

>0  An error occurred.

CONSEQUENCES OF ERRORS
Default.

The following sections are informative.

APPLICATION USAGE
Note that:

    cal 83

refers to A.D. 83, not 1983.

EXAMPLES
None.

RATIONALE
Earlier versions of this standard incorrectly required that the command:

    cal 2000

write a one-month calendar for the current calendar month (no matter what the current year is) in the year 2000 to standard output. This did not match historic practice in any known version of the cal utility. The description has been updated to match historic practice. When only the year operand is given, cal writes a twelve-month calendar for the specified year.

FUTURE DIRECTIONS
A future version of this standard may support locale-specific recognition of the date of adoption of the Gregorian calendar.

SEE ALSO
The Base Definitions volume of POSIX.1-2017, Chapter 8, Environment Variables

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

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