Here is a quick and dirty PostgreSQL ~/.pgpass parser, in Common Lisp.

It depends on Split Sequence, conveniently loaded with QuickLisp, like so.

(ql:quickload :split-sequence :silent t)

And here is the actual code. It’s not wrapped in a function, and the other connection parameters are hard coded. This can use some refactoring; particularly with relevance to error handling.

(defvar pguser "user")
(defvar pgdb "database")
(defvar pghost "hostname")
(defvar pgport 5432)

(defvar pgpass
  (handler-case
      (with-open-file 
          (.pgpass "~/.pgpass"
		   :direction :input
		   :if-does-not-exist nil)
	(flet ((wildcard-string= (a b)
		 (or (string= a "*")
		     (string= a (princ-to-string b)))))

	  (loop for line = (read-line .pgpass nil)
	    while line
	    when (destructuring-bind (host port db user passwd)
		   (split-sequence:split-sequence #\: line)
		   (if (and (wildcard-string= host pghost)
			    (wildcard-string= port pgport)
			    (wildcard-string= db pgdb)
			    (wildcard-string= user pguser))
		       passwd))
	    return it)))
    (file-error (e)
		(format *error-output* "Unable to load password file; ~A~%"
			e)
		nil)))

(format t "Password: ~A~%" pgpass)

Licenses

Split-Sequence is part of CL-Utilities and Public Domain.

QuickLisp is licensed under an MIT-style license.

The example code above is © 2015 Johann ‘Myrkraverk’ Oskarsson and licensed under the Two-clause BSD license.