from my research, bundle exec is responsible for executing a command in the context of a bundle.
anyway, I don’t quite understand yet for what it does differently for just the command rake db:migrate comparing with bundle exec rake db:migrate.
for example in my case, I executed the first command, and what I got was the following errors:
$ rake db:migrate
(in c:/rails/rails_projects/soccerweb)
rake aborted!
uninitialized constant Rake::DSL
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2482:in `const_missing'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/tasklib.rb:8:in `<clas
s:TaskLib>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/tasklib.rb:6:in `<modu
le:Rake>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/tasklib.rb:3:in `<top
(required)>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/testtask.rb:4:in `requ
ire'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/testtask.rb:4:in `<top
(required)>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/test_unit/testing.r
ake:2:in `require'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/test_unit/testing.r
ake:2:in `<top (required)>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/test_unit/railtie.r
b:12:in `load'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/test_unit/railtie.r
b:12:in `block in <class:TestUnitRailtie>'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/railtie.rb:183:in `
call'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/railtie.rb:183:in `
block in load_tasks'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/railtie.rb:183:in `
each'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/railtie.rb:183:in `
load_tasks'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/engine.rb:396:in `b
lock in load_tasks'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/application/railtie
s.rb:8:in `each'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/application/railtie
s.rb:8:in `all'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/engine.rb:396:in `l
oad_tasks'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/application.rb:103:
in `load_tasks'
c:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.1/lib/rails/railtie/configurabl
e.rb:30:in `method_missing'
c:/rails/rails_projects/soccerweb/Rakefile:7:in `<top (required)>'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `load'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
c:/Ruby192/lib/ruby/1.9.1/rake.rb:1991:in `run'
c:/Ruby192/bin/rake:31:in `<main>'
but when I used “bundle exec” preceding that “rake db:migrate” command, everything just worked for me gracefully!
anyone can shed some light on me?
bundle exec rakeruns the version ofrakewhich you’ve specified in yourGemfile. The default version ofrake, the one which can be found in your$PATH, might be different than one executed bybundle exec rake.The problem you’ve experienced has been covered in a separate question. Your
bundle exec rakemost probably runs rake 0.8.7 andrakefrom your$PATHis a newer version which is affected by this problem.Quoting from man bundle exec: