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TTY(1P) POSIX Programmer's Manual TTY(1P)
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.
tty — return user's terminal name
tty
The tty utility shall write to the standard output the name of the
terminal that is open as standard input. The name that is used shall
be equivalent to the string that would be returned by the ttyname()
function defined in the System Interfaces volume of POSIX.1‐2008.
The tty utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
None.
While no input is read from standard input, standard input shall be
examined to determine whether or not it is a terminal, and, if so, to
determine the name of the terminal.
None.
The following environment variables shall affect the execution of
tty:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions
volume of POSIX.1‐2008, 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.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
If standard input is a terminal device, a pathname of the terminal as
specified by the ttyname() function defined in the System Interfaces
volume of POSIX.1‐2008 shall be written in the following format:
"%s\n", <terminal name>
Otherwise, a message shall be written indicating that standard input
is not connected to a terminal. In the POSIX locale, the tty utility
shall use the format:
"not a tty\n"
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Standard input is a terminal.
1 Standard input is not a terminal.
>1 An error occurred.
Default.
The following sections are informative.
This utility checks the status of the file open as standard input
against that of an implementation-defined set of files. It is
possible that no match can be found, or that the match found need not
be the same file as that which was opened for standard input
(although they are the same device).
None.
None.
None.
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2008, isatty(3p), ttyname(3p)
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 .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 TTY(1P)