Open3Backport

gem 'open3_backport'

$ bundle

$ gem install open3_backport

# Block form:
Open3.popen3("echo", "a") do |stdin, stdout, stderr, wait_thr|
  pid = wait_thr.pid # pid of the started process.
  exit_status = wait_thr.value # Process::Status object returned.
end

# Non-block form:
stdin, stdout, stderr, wait_thr = Open3.popen3("echo", "a")
pid = wait_thr[:pid]  # pid of the started process.
stdin.close  # stdin, stdout and stderr should be closed explicitly in this form.
stdout.close
stderr.close
exit_status = wait_thr.value  # Process::Status object returned.

Open3.popen3("echo a") {|i, o, e, t| ... }

Open3.popen3("echo", "a") {|i, o, e, t| ... }

Open3.popen2("wc -c") do |i, o, t|
  i.print "answer to life the universe and everything"
  i.close
  p o.gets #=> "42\n"
end

Open3.popen2("bc -q") do |i, o, t|
  i.puts "obase=13"
  i.puts "6 * 9"
  p o.gets #=> "42\n"
end

Open3.popen2("dc") do |i, o, t|
  i.print "42P"
  i.close
  p o.read #=> "*"
end

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

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

image = File.read("/usr/share/openclipart/png/animals/mammals/sheep-md-v0.1.png", :binmode=>true)
thumnail, err, s = Open3.capture3("convert -thumbnail 80 png:- png:-", :stdin_data=>image, :binmode=>true)
if s.success?
  STDOUT.binmode
  print thumnail
end

# factor is a command for integer factorization.
o, s = Open3.capture2("factor", :stdin_data=>"42")
p o #=> "42: 2 3 7\n"

# generate x**2 graph in png using gnuplot.
gnuplot_commands = <<"End"
  set terminal png
  plot x**2, "-" with lines
  1 14
  2 1
  3 8
  4 5
  e
End
image, s = Open3.capture2("gnuplot", :stdin_data=>gnuplot_commands, :binmode=>true)

# capture make log
make_log, s = Open3.capture2e("make")

source = "foo.c"
Open3.popen2e("gcc", "-Wall", source) do |i, oe, t|
  oe.each do |line|
    if /warning/ =~ line
      # ...
    end
  end
end

Open3.pipeline_rw(["tr", "-dc", "A-Za-z"], ["wc", "-c"]) do |i, o, ts|
  i.puts "All persons more than a mile high to leave the court."
  i.close
  p o.gets #=> "42\n"
end

Open3.pipeline_rw("sort", "cat -n") do |stdin, stdout, wait_thrs|
  stdin.puts "foo"
  stdin.puts "bar"
  stdin.puts "baz"
  stdin.close     # send EOF to sort.
  p stdout.read   #=> "     1\tbar\n     2\tbaz\n     3\tfoo\n"
end

Open3.pipeline_r("zcat /var/log/apache2/access.log.*.gz",
                 [{"LANG"=>"C"}, "grep", "GET /favicon.ico"],
                 "logresolve") {|o, ts|
  o.each_line {|line|
    # ...
  }
}

Open3.pipeline_r("yes", "head -10") {|o, ts|
  p o.read      #=> "y\ny\ny\ny\ny\ny\ny\ny\ny\ny\n"
  p ts[0].value #=> #<Process::Status: pid 24910 SIGPIPE (signal 13)>
  p ts[1].value #=> #<Process::Status: pid 24913 exit 0>
}

Open3.pipeline_w("bzip2 -c", :out=>"/tmp/hello.bz2") {|i, ts|
  i.puts "hello"
}

# run xeyes in 10 seconds.
Open3.pipeline_start("xeyes") {|ts|
  sleep 10
  t = ts[0]
  Process.kill("TERM", t.pid)
  p t.value #=> #<Process::Status: pid 911 SIGTERM (signal 15)>
}

# convert pdf to ps and send it to a printer.
# collect error message of pdftops and lpr.
pdf_file = "paper.pdf"
printer = "printer-name"
err_r, err_w = IO.pipe
Open3.pipeline_start(["pdftops", pdf_file, "-"],
                     ["lpr", "-P#{printer}"],
                     :err=>err_w) {|ts|
  err_w.close
  p err_r.read # error messages of pdftops and lpr.
}

fname = "/usr/share/man/man1/ruby.1.gz"
p Open3.pipeline(["zcat", fname], "nroff -man", "less")
#=> [#<Process::Status: pid 11817 exit 0>,
#    #<Process::Status: pid 11820 exit 0>,
#    #<Process::Status: pid 11828 exit 0>]

fname = "/usr/share/man/man1/ls.1.gz"
Open3.pipeline(["zcat", fname], "nroff -man", "colcrt")

# convert PDF to PS and send to a printer by lpr
pdf_file = "paper.pdf"
printer = "printer-name"
Open3.pipeline(["pdftops", pdf_file, "-"],
               ["lpr", "-P#{printer}"])

# count lines
Open3.pipeline("sort", "uniq -c", :in=>"names.txt", :out=>"count")

# cyclic pipeline
r,w = IO.pipe
w.print "ibase=14\n10\n"
Open3.pipeline("bc", "tee /dev/tty", :in=>r, :out=>w)
#=> 14
#   18
#   22
#   30
#   42
#   58
#   78
#   106
#   202