From: Damphyr <damphyr@...>
Date: 2005-12-09T06:58:48+09:00
Subject: Re: getting stdout and stderr for system calls on windows

I ended up with the following after this discussion. It doesn't separate 
stderr and stdout, but for what I want it, it's more than enough. And I 
added crude benchmarking as well:) :
There was also an exitcode method in there (you can get the exitcde from 
@process).

#Executes a command on a dos shell, redirecting stderr to stdout ("2>&1")
#
#You can then access the output and the return value for the command.
#
#This is meant as a last-resort replacement for popen3 (because of 
problems with VC++6.0 and the Ruby One-Click Installer).
#
#_exec_time_ provides the Time spent running the command.
class ExecCmd
	attr_reader :output,:cmd,:exec_time
	#When a block is given, the command runs before yielding
	def initialize cmd
		@output=""
		@exec_time=0
		@cmd=cmd
		@cmd_run=cmd+" 2>&1" unless cmd=~/2>&1/
		if block_given?
			run
			yield self
		end
	end
	
	#Runs the command
	def run
		t1=Time.now
		IO.popen(@cmd_run){|f|
			@output=f.read
			@process=Process.waitpid2(f.pid)[1]
		}
		@exec_time=Time.now-t1
	end
	#Returns false if the command hasn't been executed yet
	def run?
		return false unless @process
		return true
	end
	#Returns true if the command was succesfull.
	#
	#Will return false if the command hasn't been executed
	def success?
		return @process.success? if @process
		return false
	end
end

www-data wrote:
> I have the same problem, and i'm likely going to end up using this 
> syntax inside a system call:
> 
> (((dmake target | tee stdout.txt) 3>&1 1>&2 2>&3 | tee stderr.txt) 3>&1 
> 1>&2 2>&3) 2>&1 | tee output.txt
> 
> where output.txt will contain stderr + stdout
> stdout.txt will contain stdout
> stderr.txt will contain stderr
> 
> There is a description of how this works here:
> http://www.cpqlinux.com/redirect.html
> Scroll down to "Capturing stderr with tee Swapping stderr and stdout"
> Ugly as hell but it does the trick... hopefully someone knows a cleaner 
> way to do this within ruby?
> 
> --
> 
> ara.t.howard wrote:
> 
>>On Thu, 24 Nov 2005, Damphyr wrote:
>>
>>
>>>system 'echo blabla'
>>>stdout.
>>>
>>>Cheers,
>>>V.-
>>
>>i was working on this at one point:
>>
>>   harp:~ > cat a.rb
>>   class Redirector
>>     require "tempfile"
>>     attr_accessor "ruby"
>>     def initialize
>>       @ruby = "ruby"
>>       @script = tempfile
>>       @script.write <<-ruby
>>         stdout, stderr = ARGV.shift, ARGV.shift
>>         File::unlink out rescue nil
>>         File::unlink err rescue nil
>>         STDOUT.reopen(open(stdout,"w"))
>>         STDERR.reopen(open(stderr,"w"))
>>         system(ARGV.join(' '))
>>       ruby
>>       @script.close
>>     end
>>     def run command, redirects = {}
>>       stdout = redirects.values_at("stdout", :stdout, "o", :o, 
>>1).compact.first
>>       tout = nil
>>       unless stdout
>>         tout = tempfile
>>         stdout = tout.path
>>       end
>>       stderr = redirects.values_at("stderr", :stderr, "e", :e, 
>>2).compact.first
>>       terr = nil
>>       unless stderr
>>         terr = tempfile
>>         stderr = terr.path
>>       end
>>       system "#{ @ruby } #{ @script.path } #{ stdout } #{ stderr } #{ 
>>command }"
>>       ret = IO::read(stdout), IO::read(stderr), $?.exitstatus
>>       tout.close! if tout
>>       terr.close! if terr
>>       ret
>>     end
>>     def tempfile
>>       Tempfile::new(Process::pid.to_s << rand.to_s)
>>     end
>>   end
>>
>>   redirector = Redirector::new
>>
>>   stdout, stderr, exitstatus = redirector.run "echo 42"
>>   p [stdout, stderr, exitstatus]
>>
>>   redirector.run "echo 42", 1 => "out", 2 => "err"
>>   p [IO::read("out"), IO::read("err")]
>>
>>
>>   harp:~ > ruby a.rb
>>   ["42\n", "", 0]
>>   ["42\n", ""]
>>
>>regards.
>>
>>-a
> 
> 
> 


-- 
http://www.braveworld.net/riva

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