Why do I get a Readline error when trying to start rails console?

问题

UPDATE: I probably messed up my system while trying solutions found somewhere else. I started from scratch and Ruby 1.9.3 installed without a hitch. Now to try to get ree-1.8.7 to play nice alongside...

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I'm trying to install Ruby 1.9.3 using RVM on Kubuntu (11.10 I believe). I've been having plenty of issues with Readline so far, but found the answer to all but this one.

I installed Ruby 1.9.3 this way:

rvm install 1.9.3
# Install of ruby-1.9.3-p0 - #complete 
cd ~/.rvm/src/ruby-1.9.3-p0/ext/readline/
~/.rvm/src/ruby-1.9.3-p0/ext/readline $ ../../ruby extconf.rb --with-editline-dir="/usr" --with-readline-dir="/usr"
# any other way of doing this resulted in simply readline not being loaded when trying to start the console
# I have libreadline6 and libreadline6-dev installed (and all the packages requested in `rvm requirements`
make install
# compiling readline.c                                                                                                                                                                                      
# linking shared-object readline.so                                                                                                                                                                         
# /usr/bin/install -c -m 0755 readline.so /home/mbillard/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/x86_64-linux                                                                                    
# installing default readline libraries 

So far everything looks to have run properly but when I try to start the console I get this error:

/home/mbillard/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/irb/completion.rb:9:in `require': /home/mbillard/.rvm/usr/lib/libreadline.so.6: undefined symbol: UP - /home/mbillard/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/x86_64-linux/readline.so (LoadError)
  from /home/mbillard/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/irb/completion.rb:9:in `<top (required)>'
  from /home/mbillard/.rvm/gems/ruby-1.9.3-p0@taskman/gems/railties-3.2.1/lib/rails/commands/console.rb:3:in `require'
  from /home/mbillard/.rvm/gems/ruby-1.9.3-p0@taskman/gems/railties-3.2.1/lib/rails/commands/console.rb:3:in `<top (required)>'
  from /home/mbillard/.rvm/gems/ruby-1.9.3-p0@taskman/gems/railties-3.2.1/lib/rails/commands.rb:38:in `require'
  from /home/mbillard/.rvm/gems/ruby-1.9.3-p0@taskman/gems/railties-3.2.1/lib/rails/commands.rb:38:in `<top (required)>'
  from script/rails:6:in `require'
  from script/rails:6:in `<main>'

I tried using rvm install 1.9.3 --with-readline-dir="$rvm_path/usr" and using $rvm_path when compiling Readline in the command above but those resulted in this error:

checking for tgetnum() in -lncurses... yes
checking for readline/readline.h... yes
checking for readline/history.h... yes
checking for readline() in -lreadline... no
checking for readline() in -ledit... no
checking for editline/readline.h... no

So, thanks for any help you can provide.

回答1:

Please read the output of:

rvm requirements

It will show you list of libraries you need to install to make good use of Ruby

After installing all the libs, clean rvm installed libs and reinstall Ruby:

rm -rf $rvm_path/usr
rvm reinstall 1.9.3

回答2:

You need to install the readline development packages. (This is how my answer differs from the other existing one):

apt-get install libreadline-dev

After doing so, you can reinstall Ruby (as @mpapis already mentioned) and everything should work.

rvm reinstall 1.9.3

回答3:

I had a similar issue. try

brew link readline --force

that worked for me.

I got the solution from here:

Rails Console Not Loading

来源：https://stackoverflow.com/questions/9270274/why-do-i-get-a-readline-error-when-trying-to-start-rails-console