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End of Life Ruby 3.2 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

IO#close

close → nil

Closes the stream for both reading and writing if open for either or both; returns nil. See Open and Closed Streams.

If the stream is open for writing, flushes any buffered writes to the operating system before closing.

If the stream was opened by IO.popen, sets global variable $? (child exit status).

Example:

Example
IO.popen('ruby', 'r+') do |pipe|
  puts pipe.closed?
  pipe.close
  puts $?
  puts pipe.closed?
end

Output:

false
pid 13760 exit 0
true

Related: IO#close_read, IO#close_write, IO#closed?.