tty - Returns pathname of terminal device
The tty command writes the full pathname of your terminal device to stan-
dard output. The tty command may also be used to determine if standard
input is a terminal.
Interfaces documented on this reference page conform to industry standards
Refer to the standards(5) reference page for more information about indus-
try standards and associated tags.
-s Suppresses reporting the pathname.
The XCU specification states that -s option is obsolete and recommends the
portable applications use test -t 0 instead of tty -s.
The command tty -s evaluates as TRUE if standard input is a display and
FALSE if it is not.
[Tru64 UNIX] The file /dev/tty is a special file always refers to your
controlling terminal, although it also may have another name like
/dev/console or /dev/tty2. To avoid writing undesirable output to an out-
put file--for example, to write a prompt in a shell script to the screen,
while writing the response to the prompt to an output file--redirect stan-
dard output to /dev/tty.
While the -s option is useful if only the exit code is wanted, it does not
rely on any ability to form a valid pathname. For a portable application
you should use the command test -t 0.
The following exit values are returned:
0 Successful completion.
1 Standard input is not a display.
2 [Tru64 UNIX] Invalid options specified.
>>2 [Tru64 UNIX] An error occurred.
Standard input is not a tty
[Tru64 UNIX] Your standard input is not a display and you did not
specify the -s option.
1. To display full pathname of your terminal device, enter:
2. To test whether or not the standard input is a terminal device, create
a shell script containing the following:
if tty -s
echo 'Output is a display'
echo 'Output is not a display'
If the standard input is a terminal device, this displays the Output
is a display message. If the standard input is not a terminal device,
it displays the Output is not a display message.
The following environment variables affect the execution of tty:
Provides a default value for the internationalization variables that
are unset or null. If LANG is unset or null, the corresponding value
from the default locale is used. If any of the internationalization
variables contain an invalid setting, the utility behaves as if none of
the variables had been defined.
If set to a non-empty string value, overrides the values of all the
other internationalization variables.
Determines 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).
Determines the locale for the format and contents of diagnostic mes-
sages written to standard error.
Determines the location of message catalogues for the processing of
Pseudodevice representing the user's controlling terminal.
Commands: stty(1), test(1)