I finally managed to get the 'pg' gem install after spending hours trying to figure out why it's not working...
at the end I entered sudo env ARCHFLAGS="-arch x86_64" gem install pg -v 0.12.2 -- --with-pg-config=/Applications/Postgres.app/Contents/MacOS/bin/pg_config which worked like a charm. But now I still have the same error when I try bundler - so I guess I didn't really solve the problem? Anyway, here's what bundle install is saying:
Installing pg (0.12.2)
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/Users/thomas/.rvm/rubies/ruby-1.9.3-p392/bin/ruby extconf.rb --with-pg-config=/usr/pgsql-9.2/bin/pg_config
Using config values from /usr/pgsql-9.2/bin/pg_config
sh: /usr/pgsql-9.2/bin/pg_config: No such file or directory
sh: /usr/pgsql-9.2/bin/pg_config: No such file or directory
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for PQconnectdb() in -lpq... yes
checking for PQconnectionUsedPassword()... yes
checking for PQisthreadsafe()... yes
checking for PQprepare()... yes
checking for PQexecParams()... yes
checking for PQescapeString()... yes
checking for PQescapeStringConn()... yes
checking for PQgetCancel()... yes
checking for lo_create()... yes
checking for pg_encoding_to_char()... yes
checking for PQsetClientEncoding()... yes
checking for rb_encdb_alias()... yes
checking for rb_enc_alias()... yes
checking for struct pgNotify.extra in libpq-fe.h... yes
checking for unistd.h... yes
checking for ruby/st.h... yes
creating extconf.h
creating Makefile
make
compiling compat.c
compiling pg.c
pg.c: In function ‘pgconn_wait_for_notify’:
pg.c:2117: warning: ‘rb_thread_select’ is deprecated (declared at /Users/thomas/.rvm/rubies/ruby-1.9.3-p392/include/ruby-1.9.1/ruby/intern.h:380)
pg.c: In function ‘pgconn_block’:
pg.c:2592: warning: format not a string literal and no format arguments
pg.c:2598: warning: ‘rb_thread_select’ is deprecated (declared at /Users/thomas/.rvm/rubies/ruby-1.9.3-p392/include/ruby-1.9.1/ruby/intern.h:380)
pg.c:2607: warning: format not a string literal and no format arguments
linking shared-object pg_ext.bundle
ld: warning: directory not found for option '-L-Wl,-undefined,dynamic_lookup'
Undefined symbols for architecture x86_64:
....
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
make: *** [pg_ext.bundle] Error 1
I think the problem is that bundler tries to install the gem using the pg_config from another postresql installation (which I had removed). Is there any way to ensure that bundler uses the right path?
I was stuck on my bundle install for 3 days. Tried Everything like adding env ARCHFLAGS="-arch x86_64" gem install pg -- --with-pg-config=/usr/local/Cellar/postgresql/9.3.5_1/bin/pg_config
I was able to see pg gem getting installed after this command but still it was not installing from bundle install, which was a pain because I dint know what to write in Gemfile except gem 'pg'
The thing which finally worked for me was to find that my pg_config was in /Library/PostgreSQL/9.3/bin/pg_config and by default the Gemfile bundle install looks in /usr/local/bin/pg_config
I just ran the following command and magic happened. bundle config build.pg --with-pg-config=/Library/PostgreSQL/9.3/bin/pg_config
Some correction. For those who have installed postgres using homebrew.
1) write the following line in your ~/.bash_profile
export ARCHFLAGS="-arch x86_64"
2) restart console
3) execute following command
bundle config build.pg --with-pg-config=/usr/local/Cellar/postgresql/9.3.5_1/bin/pg_config (this has to be your pg config address, can differ for each depending on versions of postgres)
4) Install pg once locally by running this command
sudo env ARCHFLAGS="-arch x86_64" gem install pg -- --with-pg-config=/usr/local/Cellar/postgresql/9.3.5_1/bin/pg_config
5) bundle install
来源：https://stackoverflow.com/questions/15234810/cannot-install-pg-gem