To change directory inside a ruby script?

I want to create a new rails application and fire up the rails 开发者_开发问答server for that application, everything from a ruby script.

My code look like this:

#!/usr/bin/env ruby
system "rails new my_app"
system "cd my_app"
system "rails server &"

However, when running "rails server &" the path is not in the my_app folder, but in the parent folder.

Is there a way to change directory inside a script so that i can run "rails server", "rake about" and "rake db:migrate" for that new application?

All work around tips would be appreciated.

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Don't listen to them, Dir.chdir("dir") will probably do the wrong thing. What you almost always want is to limit change to a particular context, without affecting the rest of the program like this:

#!/usr/bin/env ruby
system "rails new my_app"
Dir.chdir("my_app") do
  system "rails server &"
end
# back where we were, even with exception or whatever

---

Use Dir.chdir:

Dir.chdir "my_app"

---

system supports :chdir argument that allows you to specify its working directory:

system("echo Test; pwd", chdir: '/tmp')

outputs '/tmp'

---

Use Dir.chdir to change the working directory for a script.

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Why can't you just do it like this:

#!/usr/bin/env ruby
system 'rails new myapp && cd myapp && rails server &'

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The following lines have the same output:

puts Dir.chdir("/tmp") { IO.popen("ls -la") { |io| io.read } } 

puts IO.popen(["ls", "-la", "/tmp"]).read

puts IO.popen("ls -la /tmp").read

# drwxrwxrwt 25 root       root       16384 июля  23 01:17 .
# drwxr-xr-x 22 root       root        4096 июля  22 13:36 ..
# drwxrwxr-x 12 itsnikolay itsnikolay  4096 июля  19 17:14 app_template
# drwx------  2 itsnikolay itsnikolay  4096 июля  21 15:04 .com.google.Chrome.dThb8f
# drwx------  2 itsnikolay itsnikolay  4096 июля  18 20:55 .com.google.Chrome.FGDBGc

also you can run rails and create an application (this can be helpful in rspec tests and etc.):

IO.popen("cd /tmp/ && rails new test_app").read

and ever you can run a rails server ;)

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Use Dir.chdir("[aString]")