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Alessandro Cuttin
Asked: 2014-08-07 06:48:48 +0800 CST

Shell gives no prompt if auto completion is enabled (blinking cursor instead)

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I tryed to enable shell autocompletion uncommenting the following lines in my .bashrc:

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
 if ! shopt -oq posix; then
   if [ -f /usr/share/bash-completion/bash_completion ]; then
     . /usr/share/bash-completion/bash_completion
   elif [ -f /etc/bash_completion ]; then
     . /etc/bash_completion
   fi
 fi

However, this have a side effect. Even though autocomplete seems to work, when I open a new terminal, only a blinking cursor is presented:

enter image description here

I am returned to the usual user@machine:~$ prompt only after pressing Ctrl+C.

The normal behavior is restored if I comment the above lines (but no autocompletion any more).

I can't figure out what the problem is.

--Update 1--

Here's what the code does:

enter image description here

--Update 2--

Here's the output of the suggested commands. Somethings keeps looping and the terminal is flooded by the ouptut.

++++++ : /etc/bash_completion.d
++++++ readonly BASH_COMPLETION_COMPAT_DIR
++++++ _blacklist_glob='@(acroread.sh)'
++++++ shopt -s extglob progcomp
++++++ complete -d pushd
++++++ complete -u write chfn groups slay w sux runuser
++++++ complete -A stopped -P '"%' -S '"' bg
++++++ complete -j -P '"%' -S '"' fg jobs disown
++++++ complete -v readonly unset
++++++ complete -A setopt set
++++++ complete -A shopt shopt
++++++ complete -A helptopic help
++++++ complete -a unalias
++++++ complete -A binding bind
++++++ complete -c command type which
++++++ complete -b builtin
++++++ [[ linux-gnu == *@(solaris|aix)* ]]
++++++ [[ linux-gnu == *@(solaris|aix)* ]]
++++++ [[ linux-gnu == *@(solaris|aix)* ]]
++++++ _backup_glob='@(#*#|*@(~|.@(bak|orig|rej|swp|dpkg*|rpm@(orig|new|save))))'
++++++ complete -F _service service
++++++ _sysvdirs
++++++ sysvdirs=()
++++++ [[ -d /etc/rc.d/init.d ]]
++++++ [[ -d /etc/init.d ]]
++++++ sysvdirs+=(/etc/init.d)
++++++ [[ -f /etc/slackware-version ]]
++++++ for svcdir in '${sysvdirs[@]}'
++++++ for svc in '$svcdir/!($_backup_glob)'
++++++ [[ -x /etc/init.d/acpid ]]
++++++ complete -F _service /etc/init.d/acpid
++++++ for svc in '$svcdir/!($_backup_glob)'
++++++ [[ -x /etc/init.d/anacron ]]
++++++ complete -F _service /etc/init.d/anacron
++++++ for svc in '$svcdir/!($_backup_glob)'
++++++ [[ -x /etc/init.d/apparmor ]]

--Update 3--

Here's the requested output:

ac@ac:~$ grep -r bash_completion /etc/bash_completion.d
/etc/bash_completion.d/bash.bashrc:#  if [ -f /usr/share/bash-completion/bash_completion ]; then
/etc/bash_completion.d/bash.bashrc:#    . /usr/share/bash-completion/bash_completion
/etc/bash_completion.d/bash.bashrc:#  elif [ -f /etc/bash_completion ]; then
/etc/bash_completion.d/bash.bashrc:#    . /etc/bash_completion
/etc/bash_completion.d/bash.bashrc.bak:#  if [ -f /usr/share/bash-completion/bash_completion ]; then
/etc/bash_completion.d/bash.bashrc.bak:#    . /usr/share/bash-completion/bash_completion
/etc/bash_completion.d/bash.bashrc.bak:#  elif [ -f /etc/bash_completion ]; then
/etc/bash_completion.d/bash.bashrc.bak:#    . /etc/bash_completion
/etc/bash_completion.d/inkscape:# put this file in /etc/bash_completion.d/ 
/etc/bash_completion.d/desktop-file-validate:# put this file in /etc/bash_completion.d/
/etc/bash_completion.d/bash_completion~:. /usr/share/bash-completion/bash_completion
/etc/bash_completion.d/git-completion.bash:#   bash_completion - programmable completion functions for bash 3.2+
/etc/bash_completion.d/libreoffice.sh:# Programmable bash_completion file for the main office applications
/etc/bash_completion.d/bash_completion:# . /usr/share/bash-completion/bash_completion

Indeed the last line shows what you predicted. But I don't know what to do with that file: should I delete it, or I mistakenly overwrote it? If so, what was the original content?

command-line

2 Answers

  1. For the sake of debugging you could add some echo lines to see how far through the code it gets. I'm assuming it's breaking at some point in there but it's just not doing it very loudly.

    Replace it with something like this:

     if ! shopt -oq posix; then
   echo Entering bash-completion load
   if [ -f /usr/share/bash-completion/bash_completion ]; then
     echo Sourcing /usr/share/bash-completion/bash_completion
     . /usr/share/bash-completion/bash_completion
     echo Sourced
   elif [ -f /etc/bash_completion ]; then
     echo Sourcing /etc/bash_completion
     . /etc/bash_completion
     echo Sourced
   fi
 fi
 echo Done

    In an ideal world you'll see:

    Entering bash-completion load
Sourcing /usr/share/bash-completion/bash_completion
Sourced
Done

    If it's getting caught in the bash_completion script, turn debug on and source it manually (this is assuming your terminal still works):

    set -x
. /usr/share/bash-completion/bash_completion

    That should output up to the point it breaks (or exits) and that should give you another indicator for what the actual problem is.

    • 3
  2. Best Answer

    The fact that the output you get with set -x contains so many plus signs (++++++) means that /usr/share/bash-completion/bash_completion is being re-sourced recursively.

    In other words, /usr/share/bash-completion/bash_completion is "calling" himself, resulting in a sort of infinite loop, as you noted.

    If I were you, I would check /etc/bash_completion.d looking for references to /usr/share/bash-completion/bash_completion. Specifically, here is what I would do:

    1. ls -l /etc/bash_completion.d (there must be no symlinks to /usr/share/bash-completion/bash_completion);
    2. grep -r bash_completion /etc/bash_completion.d (none of the files in /etc/bash_completion.d should source /usr/share/bash-completion/bash_completion).

    Alternatively, you can run these two commands in your shell (without bash completion enabled, of course):

    set -x
. /usr/share/bash-completion/bash_completion |& grep -E "^\++ (\.|source)"

    This will print all "imports" and will help us identify the nasty piece of code that is causing the problem.

    From the output of grep -r bash_completion /etc/bash_completion.d you can see many matches. Most of them are comments (because they start with #), but there's an interesting line:

    /etc/bash_completion.d/bash_completion~:. /usr/share/bash-completion/bash_completion

    /etc/bash_completion.d/bash_completion~ is the culprit. This is the file that is causing the recoursive re-source.

    /usr/share/bash-completion/bash_completion in fact automatically sources every file in the /etc/bash_completion.d directory. But this directory, in your case, contains the bash_completion~ file, which is sourcing /usr/share/bash-completion/bash_completion again. This results in the sort of loop that you are experiencing.

    So go ahead and delete it!

    sudo rm /etc/bash_completion.d/bash_completion~

    (Or maybe read it if you believe it contains something useful.)

    I cannot tell you why that file was in that directory. What I can tell you is that the suffix ~ means that this is a backup file. Many text editors (including Gedit) create backup copies upon saving. Probably it was left there by mistake while you were making changes.

    • 3