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instance method

IO#fcntl

fcntl(integer_cmd, argument) → integer

static VALUE
rb_io_fcntl(int argc, VALUE *argv, VALUE io)
{
    VALUE req, arg;

    rb_scan_args(argc, argv, "11", &req, &arg);
    return rb_fcntl(io, req, arg);
}

Invokes Posix system call fcntl(2), which provides a mechanism for issuing low-level commands to control or query a file-oriented I/O stream. Arguments and results are platform dependent.

If +argument is a number, its value is passed directly; if it is a string, it is interpreted as a binary sequence of bytes. (Array#pack might be a useful way to build this string.)

Not implemented on all platforms.

See also #external_encoding #fdatasync #expect #fileno also in 4.1 · 4.0 · 3.4 · 3.3 · 3.1 · 3.0

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