Forum: Ruby-core [ruby-trunk - Bug #7489][Open] Kernel.spawn sometimes executes string directly

Issue #7489 has been reported by jcaesar (Julius Caesar).

----------------------------------------
Bug #7489: Kernel.spawn sometimes executes string directly
https://bugs.ruby-lang.org/issues/7489

Author: jcaesar (Julius Caesar)
Status: Open
Priority: Normal
Assignee:
Category:
Target version:
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-linux]


Kernel.spawn throws an exception in certain cases where it shouldn't.
It seems to attempt to execute the command directly, rather than passing
it to the shell.

See the demo script below.  What should happen, when I run this script,
is that both assertions should fail, and there should be an error 
message
from the testing framework about each test.  What actually happens is
that both tests pass and the test framework reports success.

#-------------------------------
require 'test/unit'

class TestSpawn < Test::Unit::TestCase
  #> either command would work fine if executed
  # in the shell.

  def test1
    assert_raises(Errno::ENOENT) { spawn ':' }
  end

  def test2
    assert_raises(Errno::ENOENT) { spawn 'a=b true' }
  end
end
#-------------------------------

My compiler is GCC, and the output of "gcc --version" is:

  gcc-4.4.real (Debian 4.4.5-8) 4.4.5
  Copyright (C) 2010 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There 
is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

Please note that I have attached my rbconfig.rb file.

2012/12/2 jcaesar (Julius Caesar) <redmine@ruby-lang.org>:

> Bug #7489: Kernel.spawn sometimes executes string directly
> https://bugs.ruby-lang.org/issues/7489

> Kernel.spawn throws an exception in certain cases where it shouldn't.
> It seems to attempt to execute the command directly, rather than passing
> it to the shell.

Ruby invokes simple commands, command line without meta characters, 
directly
without shell.  This behavior is inherited from Perl.

We cannot remove the behavior because people assumes pid returned from
Kernel.spawn (and IO#pid for IO.popen) is the pid of invoked simple 
command.
If we use always invoke a command via shell, people will find they 
cannot
kill the command because returned pid will be the pid of shell, not the 
command.

However, Ruby 2.0 refines the algorithm to use shell or not.
So, your example will fail as you expected.

Issue #7489 has been updated by jcaesar (Julius Caesar).


Thanks for the response.  My only comment is that the
behaviour you describe is not documented (unless I'm
missing something), and should be.

By the way, I was unaware of your reply until a short
time ago.  For some reason, I was never notified
by email.

----------------------------------------
Bug #7489: Kernel.spawn sometimes executes string directly
https://bugs.ruby-lang.org/issues/7489#change-34593

Author: jcaesar (Julius Caesar)
Status: Open
Priority: Normal
Assignee:
Category:
Target version:
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-linux]


Kernel.spawn throws an exception in certain cases where it shouldn't.
It seems to attempt to execute the command directly, rather than passing
it to the shell.

See the demo script below.  What should happen, when I run this script,
is that both assertions should fail, and there should be an error 
message
from the testing framework about each test.  What actually happens is
that both tests pass and the test framework reports success.

#-------------------------------
require 'test/unit'

class TestSpawn < Test::Unit::TestCase
  #> either command would work fine if executed
  # in the shell.

  def test1
    assert_raises(Errno::ENOENT) { spawn ':' }
  end

  def test2
    assert_raises(Errno::ENOENT) { spawn 'a=b true' }
  end
end
#-------------------------------

My compiler is GCC, and the output of "gcc --version" is:

  gcc-4.4.real (Debian 4.4.5-8) 4.4.5
  Copyright (C) 2010 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There 
is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

Please note that I have attached my rbconfig.rb file.

Issue #7489 has been updated by ko1 (Koichi Sasada).

Category set to DOC
Assignee set to akr (Akira Tanaka)
Target version set to next minor

Akr-san, could you add a documentation?

----------------------------------------
Bug #7489: Kernel.spawn sometimes executes string directly
https://bugs.ruby-lang.org/issues/7489#change-36384

Author: jcaesar (Julius Caesar)
Status: Open
Priority: Normal
Assignee: akr (Akira Tanaka)
Category: DOC
Target version: next minor
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-linux]


Kernel.spawn throws an exception in certain cases where it shouldn't.
It seems to attempt to execute the command directly, rather than passing
it to the shell.

See the demo script below.  What should happen, when I run this script,
is that both assertions should fail, and there should be an error 
message
from the testing framework about each test.  What actually happens is
that both tests pass and the test framework reports success.

#-------------------------------
require 'test/unit'

class TestSpawn < Test::Unit::TestCase
  #> either command would work fine if executed
  # in the shell.

  def test1
    assert_raises(Errno::ENOENT) { spawn ':' }
  end

  def test2
    assert_raises(Errno::ENOENT) { spawn 'a=b true' }
  end
end
#-------------------------------

My compiler is GCC, and the output of "gcc --version" is:

  gcc-4.4.real (Debian 4.4.5-8) 4.4.5
  Copyright (C) 2010 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There 
is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

Please note that I have attached my rbconfig.rb file.