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tty(1p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT 

TTY(1P)                 POSIX Programmer's Manual                 TTY(1P)

PROLOG         top

       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         top

       tty — return user's terminal name

SYNOPSIS         top

       tty

DESCRIPTION         top

       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.1‐2017.

OPTIONS         top

       The tty utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.

OPERANDS         top

       None.

STDIN         top

       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.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.1‐2017, 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.

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

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       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.1‐2017 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"

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Standard input is a terminal.

        1    Standard input is not a terminal.

       >1    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       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).

EXAMPLES         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1‐2017, isatty(3p),
       ttyname(3p)

COPYRIGHT         top

       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 .

       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                2017                           TTY(1P)

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