During the rehash process, rbenv writes out the temporary file .rbenv-shim to indicate that the rehash is in progress. Then, if a parallel rbenv rehash process tries to run at the same time, it will fail because the file already exists. This guards against race conditions in parallel rehashes.

It doesn't sound like you're running multiple rbenv rehash processes in parallel, though. It seems like .rbenv-shim file was never cleaned up after a rehash that ran earlier. That earlier process might have been killed prematurely and never cleaned up after itself.

Solution: remove the file and try again.

@mislav

That earlier process might have been killed prematurely and never cleaned up after itself.

I'm wondering what can be the root cause for such scenario?

@shyjt I don't know! Maybe if you run rbenv rehash but Ctrl-C it before it finishes.

That was so weird - I've reinstalled the package and it didn't help… But when I've repeated the procedure after restart it solved this problem and never happened again…

I had this same error message on multiple servers on the same day, and in all cases deleting the file made it work again the next time.

If this is a kind of pseudo-lock file, perhaps what rbenv could do is open and actually lock the file. Then a second rbenv which comes along and sees the file could simply try to delete it before recreating it.

This has failed for me just now on an Ubuntu 16.04 server:

Relevant Ansible output:

TASK [deploy-rails : Ensure ruby 2.4.0 is installed] *******************************************
fatal: [prod1]: FAILED! => {
  "cmd": "cd; bash -lc 'MAKEOPTS=\"-j $(getconf _NPROCESSORS_ONLN)\" CONFIGURE_OPTS=\"--disable-install-rdoc\" rbenv install 2.4.0'",
  "rc": 1,
  "stderr_lines": [
    "Downloading ruby-2.4.0.tar.bz2...",
    "-> https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.0.tar.bz2",
    "Installing ruby-2.4.0...",
    "Installed ruby-2.4.0 to /home/plforums/.rbenv/versions/2.4.0",
    "",
    "rbenv: cannot rehash: /home/plforums/.rbenv/shims/.rbenv-shim exists"
  ],
  "stdout_lines": []
}

No other commands were run in parallel. Both rbenv and ruby-build are from master as of 5 minutes ago.

After SSH'ing into the server and running rbenv uninstall 2.4.0, re-running the playbook has succeeded.

This does not seem like a user error. Seems to be a race condition in rbenv or ruby-build.

I'm getting a similar error, not b/c the lock file gets clobbered, but b/c of the 2>/dev/null redirect, which according to bash clobbers /dev/null.

Just test bash.

set -o noclobber
echo >/dev/null

bash --version

GNU bash, version 4.3.11(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3 : GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

That redirections needs to be done explicity, see Safe I/O Redirection with noclobber (Unix Power Tools, 3rd Edition).

Any update on this? I still have this issue. I guess I'll check out #982 which reports to fix.

Makes me wonder how long my system has thought a rehash was already in progress O_o

I ran rbenv doctor with the command

curl -fsSL https://github.com/rbenv/rbenv-installer/raw/master/bin/rbenv-doctor | bash

and then was told this

Checking for rbenv' in PATH: /usr/local/bin/rbenv Checking for rbenv shims in PATH: not found The directory /Users/user/.rbenv/shims' must be present in PATH for rbenv to work.
Please run `rbenv init' and follow the instructions.

Checking `rbenv install' support: /usr/local/bin/rbenv-install (ruby-build 20200214)

and it worked after exporting this director to the path like this

export PATH="$PATH:/Users/user/.rbenv/shims"

@igorshtopor @mislav - One way this can happen is if you run out of disk space mid-install. Just happened to me. Stupidly left my AWS EBS to the default 8GB.

the rbenv doctor command posted above is 404'd. here is the updated command:

with curl

curl -fsSL https://github.com/rbenv/rbenv-installer/raw/HEAD/bin/rbenv-doctor | bash

alternatively, with wget

wget -q https://github.com/rbenv/rbenv-installer/raw/HEAD/bin/rbenv-doctor -O- | bash