These docs are under active development and cover the v0.20 Kobicha security model.
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tty

tty prints the name of the terminal connected to standard input.

tty [options]
$ tty
/dev/pts/3

If standard input is not a terminal — because it has been redirected from a file or a pipe — tty prints not a tty instead.

That second behaviour is the useful one: a script can run tty to find out whether it is being run interactively or as part of a pipeline, and behave accordingly.

Options

Option Effect
-s, --silent Print nothing; report the answer only through the exit status.

Exit status

Code Meaning
0 Standard input is a terminal.
1 Standard input is not a terminal.
2 A usage error.