rvm install 2.3.1  

失败
.

cd octopress

.

ruby --version

.

rvm use 2.7.0
Required ruby-2.7.0 is not installed.
To install do: 'rvm install "ruby-2.7.0"'  

记得是用2.7.0

.

dong@Ubuntu:~/octopress$ rvm install "ruby-2.7.0"  

.

dong@Ubuntu:~/octopress$ ruby --version
ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-linux]

.

dong@Ubuntu:~/octopress$ rake generate
Could not find rake-10.5.0 in any of the sources
Run `bundle install` to install missing gems.

.

dong@Ubuntu:~/octopress$ bundle install
Traceback (most recent call last):
4: from /home/dong/.rvm/rubies/ruby-2.7.0/bin/ruby_executable_hooks:22:in `<main>'
3: from /home/dong/.rvm/rubies/ruby-2.7.0/bin/ruby_executable_hooks:22:in `eval'
2: from /home/dong/.rvm/rubies/ruby-2.7.0/bin/bundle:23:in `<main>'
1: from /home/dong/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/rubygems.rb:294:in `activate_bin_path'
/home/dong/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/rubygems.rb:275:in `find_spec_for_exe': Could not find 'bundler' (1.17.3) required by your /home/dong/octopress/Gemfile.lock. (Gem::GemNotFoundException)
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:1.17.3`

.

dong@Ubuntu:~/octopress$ gem install bundler:1.17.3
Fetching bundler-1.17.3.gem
Successfully installed bundler-1.17.3
Parsing documentation for bundler-1.17.3
Installing ri documentation for bundler-1.17.3
Done installing documentation for bundler after 3 seconds
1 gem installed

.

dong@Ubuntu:~/octopress$ rake generate
Could not find rake-10.5.0 in any of the sources
Run `bundle install` to install missing gems.

.

dong@Ubuntu:~/octopress$ bundle install

.

dong@Ubuntu:~/octopress$ rake generate
rake aborted!
Gem::LoadError: You have already activated rake 13.0.1, but your Gemfile requires rake 10.5.0. Prepending `bundle exec` to your command may solve this.
/home/dong/octopress/Rakefile:2:in `<top (required)>'
(See full trace by running task with --trace)

提示失败，
但是可以加上bundle exec

dong@Ubuntu:~/octopress$bundle exec rake generate

很多警告，但是成了，
下面也一样：

bundle exec rake preview