ERROR: While executing gem ... (Gem::FilePermissionError)

Question

I have checked all the other similar answers and none was exactly like mine, neither did any of those solutions work for me.

gem environment and sudo gem environment give the same result:

RubyGems Environment:
  - RUBYGEMS VERSION: 1.5.3
  - RUBY VERSION: 1.8.7 (2011-12-28 patchlevel 357) [x86_64-linux]
  - INSTALLATION DIRECTORY: /usr/local/lib/ruby/gems/1.8
  - RUBY EXECUTABLE: /usr/local/bin/ruby
  - EXECUTABLE DIRECTORY: /usr/local/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /usr/local/lib/ruby/gems/1.8
     - /home/ava/.gem/ruby/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/

rvm -v : rvm 1.22.3

ruby -v : ruby 1.8.7

OSX 10.8.4

echo $PATH /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/home/ava/.rvm/bin:/home/ava/bin

gem install <gem-name> gives

ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions into the /usr/local/lib/ruby/gems/1.8 directory.

whereas I am able to install the same via sudo. What am I doing wrong?

UPDATE:

As per comments and this post, I ran following:

rvm implode and then re installed the stable version. rvm install 1.9.3 or any other ruby installation fails with

Error running '__rvm_make -j24',
please read /home/ava/.rvm/log/log/1378418790_ruby-1.9.3-p194/make.log
There has been an error while running make. Halting the installation.

make.log

    [2013-09-05 22:06:48] make
current path: /home/ava/.rvm/src/ruby-1.9.3-p194
command(2): make -j24
        CC = gcc
        LD = ld
        LDSHARED = gcc -shared
        CFLAGS = -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Werror-implicit-function-declaration  -fPIC
        XCFLAGS = -include ruby/config.h -include ruby/missing.h -fvisibility=hidden -DRUBY_EXPORT
        CPPFLAGS =   -I. -I.ext/include/x86_64-linux -I./include -I.
        DLDFLAGS = -Wl,-soname,libruby.so.1.9
        SOLIBS = -lpthread -lrt -ldl -lcrypt -lm
compiling main.c
compiling dmydln.c
compiling dmyencoding.c
compiling version.c
compiling miniprelude.c
compiling array.c
compiling bignum.c
compiling class.c
compiling compar.c
compiling complex.c
compiling dir.c
compiling dln_find.c
compiling enum.c
compiling enumerator.c
compiling error.c
compiling eval.c
compiling load.c
compiling proc.c
compiling file.c
:
:
:
In file included from ossl.h:213,
                 from ossl_pkcs5.c:5:
openssl_missing.h:71: error: conflicting types for ‘HMAC_CTX_copy’
/usr/local/include/openssl/hmac.h:102: error: previous declaration of ‘HMAC_CTX_copy’ was here
openssl_missing.h:95: error: conflicting types for ‘EVP_CIPHER_CTX_copy’
/usr/local/include/openssl/evp.h:459: error: previous declaration of ‘EVP_CIPHER_CTX_copy’ was here
make[2]: *** [ossl_pkcs5.o] Error 1
In file included from ossl.h:213,
                 from ossl_x509req.c:11:
:
:
:

Answer 1

To resolve the error:

ERROR: While executing gem ... (Gem::FilePermissionError) You don't have write permissions into the /usr/local/lib/ruby/gems/1.8 directory.

the following solution worked for me:

sudo gem install -n /usr/local/bin cocoapods