fish-shell/sphinx_doc_src/cmds/isatty.rst

.. _cmd-isatty:

isatty - test if a file descriptor is a tty.
============================================

Synopsis
--------

isatty [FILE DESCRIPTOR]


Description
-----------

``isatty`` tests if a file descriptor is a 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 tty, 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
docs: Add labels to all commands This allows us to use :ref: references, which don't require hardcoding it as html [ci skip] 2019-03-31 17:05:09 +08:00			`.. _cmd-isatty:`

Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00			`isatty - test if a file descriptor is a tty.`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`============================================`
Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00			`Synopsis`
			`--------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`isatty [FILE DESCRIPTOR]`
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00
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Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Description`
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Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``isatty`` tests if a file descriptor is a tty.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``FILE DESCRIPTOR`` may be either the number of a file descriptor, or one of the strings ``stdin``, ``stdout``, or ``stderr``.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`If the specified file descriptor is a tty, the exit status of the command is zero. Otherwise, the exit status is non-zero. No messages are printed to standard error.`


Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Examples`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`--------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`From an interactive shell, the commands below exit with a return value of zero:`

Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00

			`::`

			`isatty`
			`isatty stdout`
			`isatty 2`
			`echo \| isatty 1`

Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`And these will exit non-zero:`

Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00

			`::`

			`echo \| isatty`
			`isatty 9`
			`isatty stdout > file`
			`isatty 2 2> file`