Ruby Open3.capture3用法及代碼示例

capture3(*cmd)

Open3.capture3 捕獲命令的標準輸出和標準錯誤。

stdout_str, stderr_str, status = Open3.capture3([env,] cmd... [, opts])

除了 opts[:stdin_data] 和 opts[:binmode] 之外，參數 env、cmd 和 opts 被傳遞給 Open3.popen3 。請參閱 Process.spawn 。

如果指定了opts[:stdin_data]，則將其發送到命令的標準輸入。

如果opts[:binmode] 為真，則內部管道設置為二進製模式。

例子：

# dot is a command of graphviz.
graph = <<'End'
  digraph g {
    a -> b
  }
End
drawn_graph, dot_log = Open3.capture3("dot -v", :stdin_data=>graph)

o, e, s = Open3.capture3("echo abc; sort >&2", :stdin_data=>"foo\nbar\nbaz\n")
p o #=> "abc\n"
p e #=> "bar\nbaz\nfoo\n"
p s #=> #<Process::Status: pid 32682 exit 0>

# generate a thumbnail image using the convert command of ImageMagick.
# However, if the image is really stored in a file,
# system("convert", "-thumbnail", "80", "png:#{filename}", "png:-") is better
# because of reduced memory consumption.
# But if the image is stored in a DB or generated by the gnuplot Open3.capture2 example,
# Open3.capture3 should be considered.
#
image = File.read("/usr/share/openclipart/png/animals/mammals/sheep-md-v0.1.png", :binmode=>true)
thumbnail, err, s = Open3.capture3("convert -thumbnail 80 png:- png:-", :stdin_data=>image, :binmode=>true)
if s.success?
  STDOUT.binmode; print thumbnail
end