Bug #7859

Readline: Incorrect arrow key behavior in vi_editing_mode insert mode with Readline 6.2

Added by David Albert almost 3 years ago. Updated over 1 year ago.

Assignee:Kouji Takao
ruby -v:2.0.0-rc2 Backport:


I've discovered what I think is a bug in the (({Readline})) module in the standard library. When I am using (({vi_editing_mode})) in insert mode (rather than command mode), I am unable to use the up arrow to go up through history. It seems that I can only go up through history when in command mode. Additionally, pressing the down arrow while in insert mode changes to command mode, which seems odd.

Perhaps this is intended behavior for the (({Readline})) module, but if it is, I would propose changing it. I would expect the up and down arrows to scroll up and down through history in both command mode and insert mode when (({Readline.vi_editing_mode?})) is true. You can find examples of the expected behavior in bash (((%set -o vi%)) to get into vi mode), the Python REPL, and all other that I can remember using.

I've reproduced this with (({Readline})) 6.2 on Mac OS X 10.8.2 and Ubuntu precise64 with kernel version 3.2.0-37. It is worth noting that on Mac OS X with the EditLine wrapper, the (({Readline})) module works correctly although you must have the proper settings in your .editrc file because (({Readline.vi_editing_mode})) is not implemented.

Here is the code I used to test:

# readlinetest.rb
require 'readline'

trap(:INT) {
exit 0

puts "Readline::VERSION => #{Readline::VERSION}"

loop do
puts Readline.readline(">> ", true)

Example usage:

$ ruby readlinetest.rb
Readline::VERSION => 6.2


At this point, I would expect that the up arrow would put 1234 after the prompt, but instead nothing happens. Pressing the down arrow is the same as pressing escape and changes (({readline})) into command mode.

Let me know if there's anything else I can provide to help fix this. I tried jumping into the (({Readline})) module myself, but I'm not particularly familiar with how (({readline})) works and wasn't able to make much headway.


#1 Updated by Nobuyoshi Nakada almost 3 years ago

  • Description updated (diff)
  • Category set to ext
  • Status changed from Open to Assigned
  • Assignee set to Kouji Takao
  • Target version set to next minor

#2 Updated by Richard Michael over 2 years ago

I have different, but perhaps related, problems with Readline.vi_editing_mode in Ruby 1.9.3p392 with MacPorts' readline 6.2 on MacOS 10.6.8. Please let me know if I should open a new 1.9.3 bug report instead of commenting here.

Using the readlinetest.rb program in the above report, any arrow key jumps back to the first line of history and prints it's escape sequence, and ESC itself jumps back to the first line of history. (It seems the initial escape sequence, either generated by an arrow-key or ESC itself, is printing the first line.)

$ ruby tmp/readlinetest.rb
Readline::VERSION => 6.2

one[A # Up-arrow was pressed here, on the empty line; down-arrow would print ">> one[B", right-arrow ">> one[B", etc.

$ ruby tmp/readlinetest.rb
Readline::VERSION => 6.2

one # ESC was pressed here, on the empty line.

$ find $MY_RUBY_HOME -name readline.bundle -exec otool -L {} \;
/Users/testuser/.rvm/rubies/ruby-1.9.3-p392/lib/libruby.1.9.1.dylib (compatibility version 1.9.1, current version 1.9.1)
/opt/local/lib/libreadline.6.2.dylib (compatibility version 6.0.0, current version 6.2.0)
/opt/local/lib/libncurses.5.dylib (compatibility version 5.0.0, current version 5.0.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.11)
/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 227.0.0)

#3 Updated by Clifford Heath over 1 year ago

David Albert wrote:

I've discovered what I think is a bug in the (({Readline})) module in the standard library.

vi mode uses an escape character to exit insert mode, enter command mode. ANSI terminals send escape sequences (Escape [ ) for arrow keys.
vi and vim resolve this by using short timeouts; if an escape is received and there is no following [ within 500msec or so, the escape is processed, otherwise it proceeds to resolve an arrow key. The GNU readline library has the same feature: the keyseq-timeout configuration variable, usually set in your ~/.inputrc

Check whether setting this configuration variable fixes your problems. Add a line like this to ~/.inputrc:

set keyseq-timeout 500

If you want to do further research, the GNU readline code is here: http://ftp.gnu.org/gnu/readline/
Documentation of the inputrc file: http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC12

Ruby's Readline wrapper for the readline library is pretty rudimentary; for example it does not correctly handle escape sequences, nor does it restore single-character input mode after a job-control suspend (Z followed by fg). This should be entered as a separate bug.

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