mirror of
https://github.com/fish-shell/fish-shell.git
synced 2024-12-12 16:53:37 +08:00
49 lines
986 B
ReStructuredText
49 lines
986 B
ReStructuredText
.. _cmd-isatty:
|
|
|
|
isatty - test if a file descriptor is a terminal
|
|
================================================
|
|
|
|
Synopsis
|
|
--------
|
|
|
|
::
|
|
|
|
isatty [FILE DESCRIPTOR]
|
|
|
|
Description
|
|
-----------
|
|
|
|
``isatty`` tests if a file descriptor is a terminal (as opposed to a file). The name is derived from the system call of the same name, which for historical reasons refers to a teletypewriter (TTY).
|
|
|
|
``FILE DESCRIPTOR`` may be either the number of a file descriptor, or one of the strings ``stdin``, ``stdout``, or ``stderr``.
|
|
|
|
If the specified file descriptor is a terminal device, the exit status of the command is zero. Otherwise, the exit status is non-zero. No messages are printed to standard error.
|
|
|
|
|
|
Examples
|
|
--------
|
|
|
|
From an interactive shell, the commands below exit with a return value of zero:
|
|
|
|
|
|
|
|
::
|
|
|
|
isatty
|
|
isatty stdout
|
|
isatty 2
|
|
echo | isatty 1
|
|
|
|
|
|
And these will exit non-zero:
|
|
|
|
|
|
|
|
::
|
|
|
|
echo | isatty
|
|
isatty 9
|
|
isatty stdout > file
|
|
isatty 2 2> file
|
|
|