1TTY(1P) POSIX Programmer's Manual TTY(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 tty - return user's terminal name
13
15 tty
16
18 The tty utility shall write to the standard output the name of the ter‐
19 minal that is open as standard input. The name that is used shall be
20 equivalent to the string that would be returned by the ttyname() func‐
21 tion defined in the System Interfaces volume of IEEE Std 1003.1-2001.
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24 The tty utility shall conform to the Base Definitions volume of
25 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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28 None.
29
31 While no input is read from standard input, standard input shall be
32 examined to determine whether or not it is a terminal, and, if so, to
33 determine the name of the terminal.
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36 None.
37
39 The following environment variables shall affect the execution of tty:
40 LANG Provide a default value for the internationalization variables
42 that are unset or null. (See the Base Definitions volume of
43 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
44 ables for the precedence of internationalization variables used
45 to determine the values of locale categories.)
46 LC_ALL If set to a non-empty string value, override the values of all
48 the other internationalization variables.
49 LC_CTYPE
51 Determine the locale for the interpretation of sequences of
52 bytes of text data as characters (for example, single-byte as
53 opposed to multi-byte characters in arguments).
54 LC_MESSAGES
56 Determine the locale that should be used to affect the format
57 and contents of diagnostic messages written to standard error
58 and informative messages written to standard output.
59 NLSPATH
61 Determine the location of message catalogs for the processing of
62 LC_MESSAGES .
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66 Default.
67
69 If standard input is a terminal device, a pathname of the terminal as
70 specified by the ttyname() function defined in the System Interfaces
71 volume of IEEE Std 1003.1-2001 shall be written in the following for‐
72 mat:
73 "%s\n", <terminal name>
76 Otherwise, a message shall be written indicating that standard input is
78 not connected to a terminal. In the POSIX locale, the tty utility shall
79 use the format:
80 "not a tty\n"
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85 The standard error shall be used only for diagnostic messages.
86
88 None.
89
91 None.
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94 The following exit values shall be returned:
95 0 Standard input is a terminal.
97 1 Standard input is not a terminal.
99 >1 An error occurred.
101
104 Default.
105 The following sections are informative.
107
109 This utility checks the status of the file open as standard input
110 against that of an implementation-defined set of files. It is possible
111 that no match can be found, or that the match found need not be the
112 same file as that which was opened for standard input (although they
113 are the same device).
114
116 None.
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119 None.
120
122 None.
123
125 The System Interfaces volume of IEEE Std 1003.1-2001, isatty(), tty‐
126 name()
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129 Portions of this text are reprinted and reproduced in electronic form
130 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
131 -- Portable Operating System Interface (POSIX), The Open Group Base
132 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
133 Electrical and Electronics Engineers, Inc and The Open Group. In the
134 event of any discrepancy between this version and the original IEEE and
135 The Open Group Standard, the original IEEE and The Open Group Standard
136 is the referee document. The original Standard can be obtained online
137 at http://www.opengroup.org/unix/online.html .
138IEEE/The Open Group 2003 TTY(1P)