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fish-shell/doc_src/isatty.txt

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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
\section isatty isatty - test if a file or 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
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
<tt>isatty [FILE | DEVICE | FILE DESCRIPTOR NUMBER]</tt>
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
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
<tt>isatty</tt> tests if a file or file descriptor is a tty.
The argument may be in the form of a file path, device, or file descriptor
number. Without an argument, <tt>standard input</tt> is implied.
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
If the resolved file descriptor is a tty, the command returns zero. Otherwise, the command exits one. No messages are printed to standard error.
Some documentation cleanup
2013-04-22 01:13:18 +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:
<pre>
isatty
isatty stdout
isatty 2
echo | isatty /dev/fd/1
</pre>
And these will exit non-zero:
<pre>
echo | isatty
isatty /dev/fd/9
isatty stdout > file
isatty 2 2> file
</pre>
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