+# Written by Jim Meyering and Joel E. Denny
+
+# The arguments to this script should be names of files that contain
+# copyright statements to be updated. The copyright holder's name
+# defaults to "Free Softward Foundation, Inc." but may be changed to
+# any other name by using the "UPDATE_COPYRIGHT_HOLDER" environment
+# variable.
+#
+# For example, you might wish to use the update-copyright target rule
+# in maint.mk from gnulib's maintainer-makefile module.
+#
+# Iff a copyright statement is recognized in a file and the final
+# year is not the current year, then the statement is updated for the
+# new year and it is reformatted to:
+#
+# 1. Fit within 72 columns.
+# 2. Convert 2-digit years to 4-digit years by prepending "19".
+# 3. Expand copyright year intervals. (See "Environment variables"
+# below.)
+#
+# A warning is printed for every file for which no copyright
+# statement is recognized.
+#
+# Each file's copyright statement must be formated correctly in
+# order to be recognized. For example, each of these is fine:
+#
+# Copyright @copyright{} 1990-2005, 2007-2009 Free Software
+# Foundation, Inc.
+#
+# # Copyright (C) 1990-2005, 2007-2009 Free Software
+# # Foundation, Inc.
+#
+# /*
+# * Copyright © 90,2005,2007-2009
+# * Free Software Foundation, Inc.
+# */
+#
+# However, the following format is not recognized because the line
+# prefix changes after the first line:
+#
+# ## Copyright (C) 1990-2005, 2007-2009 Free Software
+# # Foundation, Inc.
+#
+# However, any correctly formatted copyright statement following
+# a non-matching copyright statements would be recognized.
+#
+# The exact conditions that a file's copyright statement must meet
+# to be recognized are:
+#
+# 1. It is the first copyright statement that meets all of the
+# following conditions. Subsequent copyright statements are
+# ignored.
+# 2. Its format is "Copyright (C)", then a list of copyright years,
+# and then the name of the copyright holder.
+# 3. The "(C)" takes one of the following forms or is omitted
+# entirely:
+#
+# A. (C)
+# B. (c)
+# C. @copyright{}
+# D. ©
+#
+# 4. The "Copyright" appears at the beginning of a line, except that it
+# may be prefixed by any sequence (e.g., a comment) of no more than
+# 5 characters -- including white space.
+# 5. Iff such a prefix is present, the same prefix appears at the
+# beginning of each remaining line within the FSF copyright
+# statement. There is one exception in order to support C-style
+# comments: if the first line's prefix contains nothing but
+# whitespace surrounding a "/*", then the prefix for all subsequent
+# lines is the same as the first line's prefix except with each of
+# "/" and possibly "*" replaced by a " ". The replacement of "*"
+# by " " is consistent throughout all subsequent lines.
+# 6. Blank lines, even if preceded by the prefix, do not appear
+# within the FSF copyright statement.
+# 7. Each copyright year is 2 or 4 digits, and years are separated by
+# commas or dashes. Whitespace may appear after commas.
+#
+# Environment variables:
+#
+# 1. If UPDATE_COPYRIGHT_FORCE=1, a recognized FSF copyright statement
+# is reformatted even if it does not need updating for the new
+# year. If unset or set to 0, only updated FSF copyright
+# statements are reformatted.
+# 2. If UPDATE_COPYRIGHT_USE_INTERVALS=1, every series of consecutive
+# copyright years (such as 90, 1991, 1992-2007, 2008) in a
+# reformatted FSF copyright statement is collapsed to a single
+# interval (such as 1990-2008). If unset or set to 0, all existing
+# copyright year intervals in a reformatted FSF copyright statement
+# are expanded instead.
+# 3. For testing purposes, you can set the assumed current year in
+# UPDATE_COPYRIGHT_YEAR.
+# 4. The default maximum line length for a copyright line is 72.
+# Set UPDATE_COPYRIGHT_MAX_LINE_LENGTH to use a different length.
+# 5. Set UPDATE_COPYRIGHT_HOLDER if the copyright holder is other
+# than "Free Software Foundation, Inc.".