Can't create model on ruby on rails

I'm starting to learn ruby on rails. the problem that i have is that i don't know why i get there while i want to create model this is the command that i tried rails generate model Book

and get this error in my ubuntu 16 terminal

/home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/railties-5.0.1/lib/rails/app_loader.rb:40: warning: Insecure world writable dir /opt in PATH, mode 040777
/home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/railties-5.0.1/lib/rails/application/configuration.rb:148:in `rescue in database_configuration': YAML syntax error occurred while parsing /home/android/ruby Tutorial/library/config/database.yml. Please note that YAML must be consistently indented using spaces. Tabs are not allowed. Error: (<unknown>): found a tab character that violate intendation while scanning a plain scalar at line 17 column 10 (RuntimeError)
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/railties-5.0.1/lib/rails/application/configuration.rb:131:in `database_configuration'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activerecord-5.0.1/lib/active_record/railtie.rb:122:in `block (2 levels) in <class:Railtie>'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/lazy_load_hooks.rb:43:in `instance_eval'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/lazy_load_hooks.rb:43:in `execute_hook'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/lazy_load_hooks.rb:50:in `block in run_load_hooks'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/lazy_load_hooks.rb:49:in `each'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/lazy_load_hooks.rb:49:in `run_load_hooks'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activerecord-5.0.1/lib/active_record/base.rb:324:in `<module:ActiveRecord>'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activerecord-5.0.1/lib/active_record/base.rb:24:in `<top (required)>'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `require'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `block in require'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:259:in `load_dependency'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `require'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:345:in `active_record_configured?'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:263:in `disconnect_database'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:97:in `preload'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:143:in `serve'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:131:in `block in run'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:125:in `loop'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application.rb:125:in `run'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/spring-2.0.0/lib/spring/application/boot.rb:19:in `<top (required)>'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from /home/android/.rbenv/versions/2.3.3/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from -e:1:in `<main>'

i also tried this

rails script/generate model Book

and i get this error:

/home/android/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/railties-5.0.1/lib/rails/app_loader.rb:40: warning: Insecure world writable dir /opt in PATH, mode 040777
rails aborted!
Don't know how to build task 'script/generate' (see --tasks)
/home/android/ruby Tutorial/library/bin/rails:9:in `require'
/home/android/ruby Tutorial/library/bin/rails:9:in `<top (required)>'
/home/android/ruby Tutorial/library/bin/spring:14:in `<top (required)>'
bin/rails:3:in `load'
bin/rails:3:in `<main>'
(See full trace by running task with --trace)