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require 'platform'
case Platform::OS
# win32/popen4 yields stdin, stdout, stderr and pid, respectively
when :win32
require 'win32/open3'
# POpen4 provides the Rubyist a single API across platforms for executing a
# command in a child process with handles on stdout, stderr, and stdin streams
# as well as access to the process ID and exit status.
#
# Consider the following example (borrowed from Open4):
#
# require 'rubygems'
# require 'popen4'
#
# status =
# POpen4::popen4("cmd") do |stdout, stderr, stdin, pid|
# stdin.puts "echo hello world!"
# stdin.puts "echo ERROR! 1>&2"
# stdin.puts "exit"
# stdin.close
#
# puts "pid : #{ pid }"
# puts "stdout : #{ stdout.read.strip }"
# puts "stderr : #{ stderr.read.strip }"
# end
#
# puts "status : #{ status.inspect }"
# puts "exitstatus : #{ status.exitstatus }"
#
module POpen4
# Starts a new process and hands IO objects representing the subprocess
# stdout, stderr, stdin streams and the pid (respectively) to the block
# supplied. If the command could not be started, return nil.
#
# The mode argument may be set to t[ext] or b[inary] and is used only on
# Windows platforms.
#
# The stdin stream and/or pid may be omitted from the block parameter list
# if they are not required.
def self.popen4(command, mode = "t") # :yields: stdout, stderr, stdin, pid
err_output = nil
Open4.popen4(command, mode) do |stdin,stdout,stderr,pid|
yield stdout, stderr, stdin, pid
# On windows we will always get an exit status of 3 unless
# we read to the end of the streams so we do this on all platforms
# so that our behavior is always the same.
stdout.read unless stdout.eof?
# On windows executing a non existent command does not raise an error
# (as in unix) so on unix we return nil instead of a status object and
# on windows we try to determine if we couldn't start the command and
# return nil instead of the Process::Status object.
stderr.rewind
err_output = stderr.read
end
return $?
end # def
end # module
else # unix popen4 yields pid, stdin, stdout and stderr, respectively
# :enddoc:
require 'open4'
module POpen4
def self.popen4(command, mode = "t")
begin
return status = Open4.popen4(command) do |pid,stdin,stdout,stderr|
yield stdout, stderr, stdin, pid
# On windows we will always get an exit status of 3 unless
# we read to the end of the streams so we do this on all platforms
# so that our behavior is always the same.
stdout.read unless stdout.eof?
stderr.read unless stderr.eof?
end
rescue Errno::ENOENT => e
# On windows executing a non existent command does not raise an error
# (as in unix) so on unix we return nil instead of a status object and
# on windows we try to determine if we couldn't start the command and
# return nil instead of the Process::Status object.
return nil
end
end #def
end #module
end
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