System() on windows

ruby-talk
1

I'm trying to figure out why a particular system command is returning
false on windows.

This works fine and returns true:

res = system('dir')

This returns false with $? being nil:

res = system('rake')

if I just run rake at the command line it works fine. I'm sure this
is something simple, but windows is not a development environment I am
used to.

Chris

2

Windows return codes where never as standardised as Unix. Plus dir is part
of the command shell, not a standalone exec.

···

On 11/25/05, snacktime <snacktime@gmail.com> wrote:

I'm trying to figure out why a particular system command is returning
false on windows.

This works fine and returns true:

res = system('dir')

This returns false with $? being nil:

res = system('rake')

3

snacktime wrote:

I'm trying to figure out why a particular system command is returning
false on windows.

This works fine and returns true:

res = system('dir')

This returns false with $? being nil:

res = system('rake')

if I just run rake at the command line it works fine. I'm sure this
is something simple, but windows is not a development environment I am
used to.

Try cmd=ExecCmd.new("rake");puts cmd.success?;puts cmd.output using the class at the end of this message (Ara's solution for grabbing the output of stderr and stdout on windows with a broken popen3 was better - giving you separate stderr und stdout - but this one has benchmarking too :slight_smile: ).

I get

false
rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb, Rakefile.rb)
d:/dev/ruby/lib/ruby/gems/1.8/gems/rake-0.6.2/lib/rake.rb:1373:in `load_rakefile'

on a directory without a rakefile, which is correct :).

system("rake") for the same directory gives a $? of 256.

···

--------
class ExecCmd
  attr_reader :output,:cmd,:exec_time
  #When a block is given, the command runs before yielding
  def initialize cmd
  @cmd=cmd
  @cmd_run=cmd+" 2>&1" unless cmd=~/2>&1/
  if block_given?
    run
    yield self
  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 the exit code for the command. Runs the command if it hasn't run yet.
  def exitcode
    run unless @process
    @process.exitstatus
  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

--
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____________________________________________________________________
http://www.freemail.gr - äùñåÜí õðçñåóßá çëåêôñïíéêïý ôá÷õäñïìåßïõ.
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4

(In response to
news:1f060c4c0511241320g4bf0af9bs16f14b86e51d358f@mail.gmail.com by
snacktime)

res = system('rake')

I call ruby scripts by
  system('cmd.exe /c rake')

Sadly, system seems to be broken many ways on windows.

kaspar

···

--
code manufacture & ruby lab at tua.ch - und andere Domains günstig und einfach online kaufen auf top-domains.ch

5

A small follow up...

Looks like as soon as you have a pipe in the command, cmd.exe is invoked
correctly: system 'echo | rails'. I came up with this after digging trough
to the actual implementation and nosing around for quite a time :wink: .. its
of course nonsensical.

k

···

--
code manufacture & ruby lab at http://www.tua.ch/ruby

6

Hi,

At Fri, 25 Nov 2005 06:21:03 +0900,
snacktime wrote in [ruby-talk:167407]:

I'm trying to figure out why a particular system command is returning
false on windows.

This works fine and returns true:

res = system('dir')

This returns false with $? being nil:

res = system('rake')

system('rake.bat')

···

--
Nobu Nakada

7

In initialize block_given? is returning false for me. Any idea why?

Chris

···

On 11/24/05, Damphyr <damphyr@freemail.gr> wrote:

Try cmd=ExecCmd.new("rake");puts cmd.success?;puts cmd.output using the
class at the end of this message (Ara's solution for grabbing the output
  of stderr and stdout on windows with a broken popen3 was better -
giving you separate stderr und stdout - but this one has benchmarking
too :slight_smile: ).

8

Kaspar Schiess wrote:

I call ruby scripts by
  system('cmd.exe /c rake')

Sadly, system seems to be broken many ways on windows.

kaspar

How is this broken? the system() method works directly with the Windows
shell. And the rake command isn't contained within the Windows shell as
an internal command. That's why system('dir') works and system('rake')
doesn't. This would seem logical in my opinion and I am far from a
Microsoft fanboy :slight_smile:

9

snacktime wrote:

Try cmd=ExecCmd.new("rake");puts cmd.success?;puts cmd.output using the
class at the end of this message (Ara's solution for grabbing the output
of stderr and stdout on windows with a broken popen3 was better -
giving you separate stderr und stdout - but this one has benchmarking
too :slight_smile: ).

In initialize block_given? is returning false for me. Any idea why?

Did you pass a block? Actually I missed cmd.run in there (what do you expect at quarter to two?).

You can do it like this:

ExecCmd.new("rake"){|cmd|
  puts cmd.success?
  puts cmd.output
}
or like this:

cmd=ExecCmd.new("rake")
cmd.run
puts cmd.success?
puts cmd.output

But a nice sideeffect of this implementation was
cmd1=ExecCmd.new("blabla")
cmd2=ExecCmd.new("blabla2")
cmd3=ExecCmd.new("blabla3")
[cmd1,cmd2,cmd3].each{|cmd|
  cmd.run
  #do stuff with it
}
And afterwards you also have a crude benchmark for each command i.e. :slight_smile:
[cmd1,cmd2,cmd3]each{|cmd|
  if cmd.run?
    status="succeeded"
    status="failed" unless cmd.success?
    puts "#{cmd.cmd} #{status} in #{cmd.exec_time}s"
    puts "Log:\n#{cmd.output}" unless cmd.success?
  else
    puts "#{cmd.cmd} was not executed"
  end
}

···

On 11/24/05, Damphyr <damphyr@freemail.gr> wrote:

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

____________________________________________________________________
http://www.freemail.gr - äùñåÜí õðçñåóßá çëåêôñïíéêïý ôá÷õäñïìåßïõ.
http://www.freemail.gr - free email service for the Greek-speaking.

10

Hi gregarican,

How is this broken? the system() method works directly with the Windows
shell. And the rake command isn't contained within the Windows shell as
an internal command. That's why system('dir') works and system('rake')
doesn't. This would seem logical in my opinion and I am far from a
Microsoft fanboy :slight_smile:

On my unix shell:

···

--------------------------
eule@makkara:~> rake
rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb,
Rakefile.rb)
/usr/local/lib/ruby/gems/1.8/gems/rake-0.5.4/lib/rake.rb:1222:in
`load_rakefile'
eule@makkara:~> irb
irb(main):001:0> system 'rake'
rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb,
Rakefile.rb)
/usr/local/lib/ruby/gems/1.8/gems/rake-0.5.4/lib/rake.rb:1222:in
`load_rakefile'
=> false
---------------------------

On windows:
---------------------------
D:\temp>rake
rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb,
Rakefile.rb)
c:/unix/ruby/lib/ruby/gems/1.8/gems/rake-0.6.2/lib/rake.rb:1373:in
`load_rakefile'
D:\temp>irb
irb(main):001:0> system 'rake'
=> false
---------------------------

I think I know how this happens and everything (having done quite some c
programming on windows), its just that I think that it breaks
expectations. I hope I could illustrate my point.

kaspar
--
code manufacture & ruby lab at tua.ch - und andere Domains günstig und einfach online kaufen auf top-domains.ch

11

gregarican wrote:

Kaspar Schiess wrote:

> I call ruby scripts by
> system('cmd.exe /c rake')
>
> Sadly, system seems to be broken many ways on windows.
>
>
> kaspar

How is this broken? the system() method works directly with the Windows
shell. And the rake command isn't contained within the Windows shell as
an internal command. That's why system('dir') works and system('rake')
doesn't.

No; system('cal') works.

12

Ya I shouldn't be up this late either. No I didn't pass the block:)

Chris

···

On 11/25/05, Damphyr <damphyr@freemail.gr> wrote:

snacktime wrote:
> On 11/24/05, Damphyr <damphyr@freemail.gr> wrote:
>
>
>>Try cmd=ExecCmd.new("rake");puts cmd.success?;puts cmd.output using the
>>class at the end of this message (Ara's solution for grabbing the output
>> of stderr and stdout on windows with a broken popen3 was better -
>>giving you separate stderr und stdout - but this one has benchmarking
>>too :slight_smile: ).
>
>
> In initialize block_given? is returning false for me. Any idea why?
>
Did you pass a block? Actually I missed cmd.run in there (what do you
expect at quarter to two?).

13

Kaspar Schiess wrote:

I think I know how this happens and everything (having done quite some c
programming on windows), its just that I think that it breaks
expectations. I hope I could illustrate my point.

kaspar

You're correct. The fact that system() works much differently under
Windows does break expectations. Good illustration!