Errno::EEXIST File Exists error when installing 'ferret' gem from local .gem file - ruby

Question

I am trying to install the ferret ruby gem on a RHEL zlinux (s390x architecture) machine, and am trying to install a .gem file after patching it so that it will compile.
But even trying to install the pristine fetched gem, it fails as follows:
[ me#s390x ]$ sudo gem fetch ferret
Downloaded ferret-0.11.6
[ me#s390x ]$ sudo gem install -lV ferret-0.11.6.gem
Installing gem ferret-0.11.6
Using local gem /home/rubyusr/rubygems/gems/cache/ferret-0.11.6.gem
/home/rubyusr/rubygems/gems/gems/ferret-0.11.6/bin
ERROR: While executing gem ... (Errno::EEXIST)
File exists - /home/rubyusr/rubygems/gems/gems/ferret-0.11.6/bin
None of the above-mentioned directories or files related to "ferret" existed before running this command.
Also strange is that /home/rubyusr/rubygems/gems/gems/ferret-0.11.6/bin is a directory, although maybe that is a normal complaint.
A final complicating factor is when I run the gem command I am actually running a shell script that sets the environment variables for my unusual rubygems directory (I haven't had any problems so far with this set up). Here is my gem shell script:
#!/bin/bash
export GEM_HOME=/home/rubyusr/rubygems/gems
export GEM_PREFIX=/home/rubyusr/rubygems
export RUBYLIB=$GEM_PREFIX/lib:/usr/lib/ruby:/usr/lib/ruby/site_ruby:/usr/lib/site_ruby
export GEM_PATH=$GEM_HOME
OUR_GEM_COMMAND=$GEM_PREFIX/bin/gem
$OUR_GEM_COMMAND $#
EDIT:
I forgot to add that running the gem install command normally does not seem to result in this error (but ferret fails to compile), with the error:
posh.h:515:4: error: #error POSH cannot determine target CPU

Answer 1

There is a bug in Debian asking for adding support for arm64:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=770922
It needs adding a few lines in the file ext/posh.h to add support for that CPU:
--- a/ext/posh.h
+++ b/ext/posh.h
## -512,6 +512,11 ##
# define POSH_CPU_STRING "PA-RISC"
#endif
+#if defined __aarch64__
+# define POSH_CPU_AARCH64 1
+# define POSH_CPU_STRING "AArch64"
+#endif
+
#if !defined POSH_CPU_STRING
# error POSH cannot determine target CPU
# define POSH_CPU_STRING "Unknown" /* this is here for Doxygen's benefit */
Adding support for s390 was about adding these lines:
#if defined __s390__
# define POSH_CPU_S390 1
# define POSH_CPU_STRING "S/390"
#endif
if you know the corresponding values for S390/X, you can add them in there.