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.TH CAL "1P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH 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.

.SH NAME
cal
\(em print a calendar
.SH SYNOPSIS
.LP
.nf
cal \fB[[\fImonth\fB] \fIyear\fB]\fR
.fi
.SH DESCRIPTION
The
.IR 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.
.P
If no operands are given,
.IR cal
shall produce a one-month calendar for the current month in the
current year. If only the
.IR year
operand is given,
.IR cal
shall produce a calendar for all twelve months in the given calendar
year. If both
.IR month
and
.IR year
operands are given,
.IR cal
shall produce a one-month calendar for the given month in the given year.
.SH OPTIONS
None.
.SH OPERANDS
The following operands shall be supported:
.IP "\fImonth\fR" 10
Specify the month to be displayed, represented as a decimal integer
from 1 (January) to 12 (December).
.IP "\fIyear\fR" 10
Specify the year for which the calendar is displayed, represented as a
decimal integer from 1 to 9999.
.SH STDIN
Not used.
.SH "INPUT FILES"
None.
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR cal :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2008,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
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).
.IP "\fILC_MESSAGES\fP" 10
.br
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.
.IP "\fILC_TIME\fP" 10
Determine the format and contents of the calendar.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.IP "\fITZ\fP" 10
Determine the timezone used to calculate the value of the current
month.
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
The standard output shall be used to display the calendar, in an
unspecified format.
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
None.
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
Successful completion.
.IP >0 6
An error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
Note that:
.sp
.RS 4
.nf
\fB
cal 83
.fi \fR
.P
.RE
.P
refers to A.D. 83, not 1983.
.SH EXAMPLES
None.
.SH RATIONALE
Earlier versions of this standard incorrectly required that the command:
.sp
.RS 4
.nf
\fB
cal 2000
.fi \fR
.P
.RE
.P
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
.IR cal
utility. The description has been updated to match historic practice.
When only the
.IR year
operand is given,
.IR cal
writes a twelve-month calendar for the specified year.
.SH "FUTURE DIRECTIONS"
A future version of this standard may support locale-specific
recognition of the date of adoption of the Gregorian calendar.
.SH "SEE ALSO"
The Base Definitions volume of POSIX.1\(hy2008,
.IR "Chapter 8" ", " "Environment Variables"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

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