mirror of https://github.com/mkerrisk/man-pages
148 lines
4.0 KiB
Groff
148 lines
4.0 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "TTY" 1P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" tty
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.SH NAME
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tty \- return user's terminal name
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.SH SYNOPSIS
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.LP
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\fBtty\fP
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.SH DESCRIPTION
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.LP
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The \fItty\fP utility shall write to the standard output the name
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of the terminal that is open as standard input. The name that
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is used shall be equivalent to the string that would be returned by
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the \fIttyname\fP()
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function defined in the System Interfaces volume of IEEE\ Std\ 1003.1-2001.
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.SH OPTIONS
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.LP
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The \fItty\fP utility shall conform to the Base Definitions volume
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of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.SH OPERANDS
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.LP
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None.
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.SH STDIN
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.LP
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While no input is read from standard input, standard input shall be
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examined to determine whether or not it is a terminal, and,
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if so, to determine the name of the terminal.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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The following environment variables shall affect the execution of
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\fItty\fP:
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.TP 7
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\fILANG\fP
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Provide a default value for the internationalization variables that
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are unset or null. (See the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
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for
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the precedence of internationalization variables used to determine
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the values of locale categories.)
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.TP 7
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\fILC_ALL\fP
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If set to a non-empty string value, override the values of all the
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other internationalization variables.
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.TP 7
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\fILC_CTYPE\fP
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Determine the locale for the interpretation of sequences of bytes
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of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).
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.TP 7
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\fILC_MESSAGES\fP
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Determine the locale that should be used to affect the format and
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contents of diagnostic messages written to standard error and
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informative messages written to standard output.
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.TP 7
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\fINLSPATH\fP
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Determine the location of message catalogs for the processing of \fILC_MESSAGES
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\&.\fP
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.sp
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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If standard input is a terminal device, a pathname of the terminal
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as specified by the \fIttyname\fP() function defined in the System
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Interfaces volume of IEEE\ Std\ 1003.1-2001
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shall be written in the following format:
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.sp
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.RS
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.nf
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\fB"%s\\n", <\fP\fIterminal name\fP\fB>
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\fP
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.fi
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.RE
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.LP
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Otherwise, a message shall be written indicating that standard input
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is not connected to a terminal. In the POSIX locale, the
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\fItty\fP utility shall use the format:
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.sp
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.RS
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.nf
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\fB"not a tty\\n"
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\fP
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.fi
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.RE
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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The following exit values shall be returned:
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.TP 7
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\ 0
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Standard input is a terminal.
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.TP 7
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\ 1
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Standard input is not a terminal.
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.TP 7
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>1
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An error occurred.
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.sp
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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This utility checks the status of the file open as standard input
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against that of an implementation-defined set of files. It is
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possible that no match can be found, or that the match found need
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not be the same file as that which was opened for standard input
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(although they are the same device).
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.SH EXAMPLES
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.LP
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None.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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The System Interfaces volume of IEEE\ Std\ 1003.1-2001, \fIisatty\fP(),
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\fIttyname\fP()
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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