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fd

fd(stream)

Returns the file descriptor backing the stream or file. Note that this function only applies to synchronous File's and IOStream's not to any of the asynchronous streams.

Examples

In the Julia programming language, the function fd(stream)

Returns the file descriptor backing the specified stream or file. Please note that this function is applicable only to synchronous Files and IOStreams and not to any of the asynchronous streams.

julia> file = open("example.txt", "w");
julia> fd(file)
8

julia> io = IOBuffer("Hello, World!");
julia> fd(io)
-1

Here are a few examples of how to use the fd function:

1. Get the file descriptor of a file:

   julia> file = open("data.txt", "r");
   julia> fd(file)
   3

   This example obtains the file descriptor of the opened file "data.txt".

2. Get the file descriptor of an IOStream:

   julia> io = IOStream(stdout);
   julia> fd(io)
   1

   It returns the file descriptor associated with the standard output stream.

3. Handle asynchronous streams (error case):

   julia> pipe_in, pipe_out = Pipe();
   julia> fd(pipe_out)
   ERROR: ArgumentError: fd is not defined for asynchronous streams

   The fd function cannot be used with asynchronous streams like Pipe. It will throw an error if attempted.

Please note that the returned file descriptor value may vary depending on the system and the specific stream or file being used.

See Also

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