From: Damphyr <damphyr@...>
Date: 2006-02-24T00:21:15+09:00
Subject: Re: system() help

Well all of this is nice if you work on Unix/Linux/OS X.
On windows the case is a bit harder:
There's a mismatch between compilers (VC6.0 vs VC7.0) with the 
one-click-installer and popen3 so that it crashes badly.
1.8.4 might fix it if it switches to VC7.0.
So no way to separate stdout from stderr.
I used the following for windows:

#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) do |f|
           @output=f.read
           @process=Process.waitpid2(f.pid)[1]
         end
         @exec_time=Time.now-t1
         return @process.success?
       end
       #Returns false if the command hasn't been executed yet
       def run?
         return false unless @process
         return true
       end
       #Returns the exit code for the command.
       #
       #Returns nil if the command hasn't run yet.
       def exitcode
         return @process.exitstatus if @process
         return nil
       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


Gennady Bystritsky wrote:
>  
> 
>> -----Original Message-----
>> From: Gennady Bystritsky 
>> Sent: Tuesday, February 21, 2006 12:45
>> To: ruby-talk ML
>> Subject: Re: system() help
>>
>> system() does not do anyting with stdout or stdin, and it 
>> returns true or false depending on the command exit code. If 
>> you want to collect the program's stdin, the easiest way 
>                                                     ^^^^^ stdout, of
> course
>> would be to use backquotes:
>>
>> @myresult = `ls`
>>
>> If you want to collect stderr as well, depending on you 
>> system shell you can do something like:
>>
>> @myresult = `command_writing_to_stderr 2>&1`
>>
>> Or you can deal with forking and exec-ing a command 
>> explicitelly, using
>> pipe() and redirecting stdout/stderr anyway you like (you may 
>> also want to take a look at popen()).
>>
>> Gennady.
>>
>>> -----Original Message-----
>>> From: list-bounce@example.com
>>> [mailto:list-bounce@example.com] On Behalf Of zac elston
>>> Sent: Tuesday, February 21, 2006 12:27
>>> To: ruby-talk ML
>>> Subject: system() help
>>>
>>> are there any docs describing how to get stderr vs stdout from a 
>>> system()?
>>>
>>> @myresult = system(mycmd)
>>> works only if I have stdout returned but not stderr.
>>>
>>> thanks
>>>
>>> --
>>> Posted via http://www.ruby-forum.com/.
>>>
>>>
>>
> 
> 


-- 
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