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Editorial Team
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Asked: 2026-06-09T08:20:24+00:00

I have been trying for some time now to get my Rails development environment

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I have been trying for some time now to get my Rails development environment back up since I upgraded from Lion to Mountain Lion. The problem is specifically installing the pg-0.14.0 (postgresql) gem.

I have tried the instructions on this post but with no luck. I have tried uninstalling Postgres with Homebrew and then reinstalling it. Nothing is working. If I try to install this gem I recieve this error:

Building native extensions.  This could take a while...
ERROR:  Error installing pg: ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for pg_config... yes 
Using config values from /usr/local/bin/pg_config
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for pg_config_manual.h... yes
checking for PQconnectdb() in -lpq... no
checking for PQconnectdb() in -llibpq... no
checking for PQconnectdb() in -lms/libpq... no
Can't find the PostgreSQL client library (libpq)

*** 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.

Where can I find mkmf.log? Can anyone give me a suggestion on how to install the pg gem again?

update
I was able to locate my mkmf.log file using :

find / -name mkmf.log 2>/dev/null

There are several failed xcrun calls like the one below:

have_library: checking for PQconnectdb() in -llibpq… ——————– no

"xcrun cc -o conftest -I.
-I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin12.0
-I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -I/usr/local/Cellar/postgresql/9.1.4/include -arch i386 -arch x86_64 -g -Os -pipe -fno-common -DENABLE_DTRACE -fno-common -pipe -fno-common conftest.c -L. -L/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib -L. -arch i386 -arch x86_64 -L/usr/local/Cellar/postgresql/9.1.4/lib -lruby -llibpq -lpthread -ldl -lobjc " ld: library not found for -llibpq clang: error: linker command failed with exit code 1 (use -v to see invocation)

Why am I getting errors when running xcrun? Has anyone seen this?

Thanks!

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1 Answer

  1. Editorial Team

    I got this resolved finally. I used RVM to uninstall ruby and re-install ruby version 1.9.3. This allowed me to run ‘bundle install’ without a problem. I checked that all gems where loaded (gem list). However my rails application could not locate the postgres socket file at this point. The same problem is detailed here. Rather than locating the postgresql.conf file, changing permissions on it, and editing it I just uninstalled my current version of Postgres and downloaded the latest One-Click installer from PostGres. When I ran the installer again it detected the other PostGres installation and updated it. This updated the configurations for me and all is well again.

    I hope this might help some other poor rails dev upgrading to Mountain Lion 🙂

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