TTY(1P)

🌸 TTY(1P) — the POSIX Programmer's Manual, but make it make sense 💅

okay bestie, quick vibe check before we start: this page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go read the corresponding Linux manual page for the tea on Linux behavior), or honestly the interface may not be implemented on Linux at all. Not every glow-up makes it to every platform, iykyk. 🦋

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✨ NAME ✨

tty — return user's terminal name

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🎀 SYNOPSIS 🎀

tty

that's it. that's the whole thing. no args, no flags, no drama. main character energy fr fr. 👑

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💖 DESCRIPTION 💖

okay so here's what's happening: the tty utility shall write to the standard output the name of the terminal that is open as standard input. that's the whole job. it's giving "just tell me where I am."

and the name that gets 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. so it's not vibes-based, it's spec-based. 🌈

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✨ OPTIONS ✨

the tty utility shall conform to the Base Definitions volume of POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines. that's it. no options, no little flags to collect. she's minimal and she ate. 🎀

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🌸 OPERANDS 🌸

None. zero. not a single one. 💀

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🧚 STDIN 🧚

so like, while no input is read from standard input, standard input shall still be examined — to determine whether or not it is a terminal, and, if so, to determine the name of the terminal.

she's not reading your input, bestie, she's looking at it. 👀 no cap.

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🦋 INPUT FILES 🦋

None.

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💜 ENVIRONMENT VARIABLES 💜

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. she said "I'm the boss now" and meant it. 💅
• 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.

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⭐ ASYNCHRONOUS EVENTS ⭐

Default.

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🔥 STDOUT 🔥

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"

and honestly? iconic. the sassiest error string in the whole standard. 😭

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🌈 STDERR 🌈

the standard error shall be used only for diagnostic messages.

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🍓 OUTPUT FILES 🍓

None.

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✨ EXTENDED DESCRIPTION ✨

None.

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👑 EXIT STATUS 👑

the following exit values shall be returned:

1. 0 — standard input is a terminal.
2. 1 — standard input is not a terminal.
3. >1 — an error occurred.

okay so lowkey the exit status is the whole personality of this utility. 0 means yes queen you're on a terminal, 1 means nope bestie, and anything above 1 means something went wrong. script accordingly. 💖

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💀 CONSEQUENCES OF ERRORS 💀

Default.

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the following sections are informative. 🫶 (yes that means they're the bonus lore, not the rules. still read them tho.)

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🎀 APPLICATION USAGE 🎀

this utility checks the status of the file open as standard input against that of an implementation-defined set of files. and here's the tea: 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).

so like… close, but don't assume it's the literal same file, bestie. same device, different file. it's giving identical twins. 👯

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🌸 EXAMPLES 🌸

None.

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🧚 RATIONALE 🧚

None.

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🦋 FUTURE DIRECTIONS 🦋

None.

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💜 SEE ALSO 💜

• 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(), ttyname()

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⭐ COPYRIGHT ⭐

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 .

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and that's the whole page, bestie. ✨ this one comes to you from IEEE/The Open Group, dated 2017, page TTY(1P). go check if you're on a terminal, drink some water, and slay the rest of your day. 💖🎀🦋