fish-shell/doc_src/isatty.txt

\section isatty isatty - test if a file descriptor is a tty.

\subsection isatty-synopsis Synopsis
\fish{synopsis}
isatty [FILE DESCRIPTOR]
\endfish

\subsection isatty-description 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.


\subsection isatty-examples Examples

From an interactive shell, the commands below exit with a return value of zero:

\fish
isatty
isatty stdout
isatty 2
echo | isatty 1
\endfish

And these will exit non-zero:

\fish
echo | isatty
isatty 9
isatty stdout > file
isatty 2 2> file
\endfish
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`\section isatty isatty - test if a file descriptor is a tty.`
Unly use classifications in ls if stdout is a tty darcs-hash:20060919165317-ac50b-c7923c7f5900ecc9814756743e6b0345efa382c5.gz 2006-09-19 16:53:17 +00:00
			`\subsection isatty-synopsis Synopsis`
Simplify styling 2014-08-01 12:25:41 +00:00			`\fish{synopsis}`
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`isatty [FILE DESCRIPTOR]`
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options. 2014-08-01 02:37:32 +00:00			`\endfish`
Unly use classifications in ls if stdout is a tty darcs-hash:20060919165317-ac50b-c7923c7f5900ecc9814756743e6b0345efa382c5.gz 2006-09-19 16:53:17 +00:00
Some documentation cleanup 2013-04-22 01:13:18 +00:00			`\subsection isatty-description Description`
Make line length, wrapping and spacing consistent 2014-08-19 12:41:23 +00:00
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`isatty` tests if a file descriptor is a tty.
Unly use classifications in ls if stdout is a tty darcs-hash:20060919165317-ac50b-c7923c7f5900ecc9814756743e6b0345efa382c5.gz 2006-09-19 16:53:17 +00:00
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`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.`
Some documentation cleanup 2013-04-22 01:13:18 +00:00
Make line length, wrapping and spacing consistent 2014-08-19 12:41:23 +00:00
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00			`\subsection isatty-examples Examples`
Unly use classifications in ls if stdout is a tty darcs-hash:20060919165317-ac50b-c7923c7f5900ecc9814756743e6b0345efa382c5.gz 2006-09-19 16:53:17 +00:00
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00			`From an interactive shell, the commands below exit with a return value of zero:`
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options. 2014-08-01 02:37:32 +00:00
			`\fish`
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00			`isatty`
			`isatty stdout`
			`isatty 2`
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`echo \| isatty 1`
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options. 2014-08-01 02:37:32 +00:00			`\endfish`
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00
			`And these will exit non-zero:`
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options. 2014-08-01 02:37:32 +00:00
			`\fish`
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00			`echo \| isatty`
isatty: revert to previous behaviour This partially reverts commit 60808a4820b1714. 2015-02-01 09:11:44 +00:00			`isatty 9`
Enhance/fix `isatty` using `command test`. Presently, `isatty` only works on a handful of keywords. Here it is rewritten to be able to take any path, device or fd number as an argument, and eliminates errors printed to stdout. Per discussion in #1228, using `builtin test -c` within a pipe to test special file descriptors is not viable, so this implementation specifcially uses `command test`. Additionally, a note has been added to the documentation of `test` regarding this potential aberration from the expected output of the test utility under the 'Standards' section. 2014-01-08 03:57:49 +00:00			`isatty stdout > file`
			`isatty 2 2> file`
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options. 2014-08-01 02:37:32 +00:00			`\endfish`