gallery3 install on mac would not find mysql on "localhost"

mac os 10.6.8 (snowleopard)
php 5.3.8
mysql Ver 14.14 Distrib 5.5.21, for osx10.6 (i386) using readline 5.1

(mysql user and password established for gallery@localhost, @127.0.0.1 and others, but no database or tables created)

attempt to install (from cli) failed with (default) host localhost

% php index.php -u gallery -p gallery
Oops! Something went wrong during the installation:

==> Unable to connect to the database.
No such file or directory

For help ...
** INSTALLATION FAILED **

BUT using numeric host 127.0.0.1 succeeds

% php index.php -u gallery -p gallery -h 127.0.0.1
. . . (some few seconds pass here)
Your Gallery has been successfully installed!
We've created an account for you to use:
username: admin
password: <######>

As far as I can tell, the failure was in being unable to evaluate the name "localhost" and turn it into an address. The connect attempt fails.