From cb3a70735e2d1532380a420803c9c21732e0a20c Mon Sep 17 00:00:00 2001
From: giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8>
Date: Fri, 12 Apr 2013 02:43:39 +0000
Subject: Make Perl programs find the Perl interpreter via PATH

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1878 9d0c8265-081b-0410-96cb-a4ca84ce46f8
---
 editor/ppmfade | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

(limited to 'editor/ppmfade')

diff --git a/editor/ppmfade b/editor/ppmfade
index fbc62968..027fc793 100755
--- a/editor/ppmfade
+++ b/editor/ppmfade
@@ -1,5 +1,31 @@
-#!/usr/bin/perl -w
-#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+#!/bin/sh
+
+##############################################################################
+# This is essentially a Perl program.  We exec the Perl interpreter specifying
+# this same file as the Perl program and use the -x option to cause the Perl
+# interpreter to skip down to the Perl code.  The reason we do this instead of
+# just making /usr/bin/perl the script interpreter (instead of /bin/sh) is
+# that the user may have multiple Perl interpreters and the one he wants to
+# use is properly located in the PATH.  The user's choice of Perl interpreter
+# may be crucial, such as when the user also has a PERL5LIB environment
+# variable and it selects modules that work with only a certain main
+# interpreter program.
+#
+# An alternative some people use is to have /usr/bin/env as the script
+# interpreter.  We don't do that because we think the existence and
+# compatibility of /bin/sh is more reliable.
+#
+# Note that we aren't concerned about efficiency because the user who needs
+# high efficiency can use directly the programs that this program invokes.
+#
+##############################################################################
+
+exec perl -w -x -S -- "$0" "$@"
+
+#!/usr/bin/perl
+##############################################################################
+#                                  ppmfade
+##############################################################################
 #
 #  This program creates a fade (a sequence of frames) between two images.
 #
@@ -12,7 +38,7 @@
 #  much the same thing, but handles non-Netpbm formats too, and is 
 #  implemented in a more primitive language.
 #
-#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+##############################################################################
 use strict;
 
 my $SPREAD =  1;
-- 
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