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33 lines
862 B
Text
33 lines
862 B
Text
\section isatty isatty - test if a file or file descriptor is a tty.
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\subsection isatty-synopsis Synopsis
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\fish{synopsis}
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isatty [FILE | DEVICE | FILE DESCRIPTOR NUMBER]
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\endfish
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\subsection isatty-description Description
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`isatty` tests if a file or file descriptor is a tty.
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The argument may be in the form of a file path, device, or file descriptor
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number. Without an argument, `standard input` is implied.
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If the resolved file descriptor is a tty, the command returns zero. Otherwise, the command exits one. No messages are printed to standard error.
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\subsection isatty-examples Examples
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From an interactive shell, the commands below exit with a return value of zero:
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\fish
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isatty
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isatty stdout
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isatty 2
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echo | isatty /dev/fd/1
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\endfish
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And these will exit non-zero:
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\fish
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echo | isatty
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isatty /dev/fd/9
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isatty stdout > file
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isatty 2 2> file
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\endfish
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