why do I get the error when installing the gem 'pg'? [duplicate]

Question

Possible Duplicate:
Unable to install pg gem on ubuntu - Can’t find the 'libpq-fe.h header

I'm trying to add the gem pg to my local environment.
But it returns this error

Errno::EACCES: Permission denied - /Users/me/.rvm/gems/ruby-1.9.3-p362/gems/pg-0.14.1/.gemtest
An error occurred while installing pg (0.14.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.14.1'` succeeds before bundling.

What should I do?

after that error has gone, now it returns this error

Installing pg (0.14.1) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /Users/me/.rvm/rubies/ruby-1.9.3-p362/bin/ruby extconf.rb 
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/Users/me/.rvm/rubies/ruby-1.9.3-p362/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config


Gem files will remain installed in /Users/me/.rvm/gems/ruby-1.9.3-p362/gems/pg-0.14.1 for inspection.
Results logged to /Users/me/.rvm/gems/ruby-1.9.3-p362/gems/pg-0.14.1/ext/gem_make.out
An error occurred while installing pg (0.14.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.14.1'` succeeds before bundling.

Answer 1

I believe you are messing around with sudo before
try

chown -R `whoami`:staff ~/.rvm/gems/ruby-1.9.3-p362/gems

Answer 2

It looks like someone tried to install it in the past as sudo. I'd check the permissions of that directory, and chown the files if they look wrong.