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close_read 

        # IO.close_read

(from ruby core)
---
    ios.close_read    -> nil

---

Closes the read end of a duplex I/O stream (i.e., one that contains both
a read and a write stream, such as a pipe). Will raise an IOError if the
stream is not duplexed.

    f = IO.popen("/bin/sh","r+")
    f.close_read
    f.readlines

*produces:*

    prog.rb:3:in `readlines': not opened for reading (IOError)
     from prog.rb:3

Calling this method on closed IO object is just ignored since Ruby 2.3.

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