1 files changed, 45 insertions, 19 deletions

diff --git a/editor/pnmquant b/editor/pnmquant
index 5edbe85e..93d452cd 100755
--- a/editor/pnmquant
+++ b/editor/pnmquant
@@ -1,6 +1,29 @@
-#!/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
+##############################################################################
 #                         pnmquant 
 ##############################################################################
 #  By Bryan Henderson, San Jose CA; December 2001.
@@ -11,7 +34,6 @@
 use strict;
 use English;
 use Getopt::Long;
-#use File::Temp "tempfile";  # not available before Perl 5.6.1
 use File::Spec;
 #use Fcntl ":seek";  # not available in Perl 5.00503
 use Fcntl;  # gets open flags
@@ -22,22 +44,26 @@ my ($SEEK_SET, $SEEK_CUR, $SEEK_END) = (0, 1, 2);
 
 sub tempFile($) {
 
-# Here's what we'd do if we could expect Perl 5.6.1 or later, instead
-# of calling this subroutine:
-#    my ($file, $filename) = tempfile("pnmquant_XXXX", 
-#                                     SUFFIX=>".pnm", 
-#                                     DIR=>File::Spec->tmpdir())
-#                                     UNLINK=>$TRUE);
-    my ($suffix) = @_;
-    my $fileName;
-    local *file;  # For some inexplicable reason, must be local, not my
-    my $i;
-    $i = 0;
-    do {
-        $fileName = File::Spec->tmpdir() . "/pnmquant_" . $i++ . $suffix;
-    } until sysopen(*file, $fileName, O_RDWR|O_CREAT|O_EXCL);
-
-    return(*file, $fileName);
+    # We trust Perl's File::Temp to do a better job of creating the temp
+    # file, but it doesn't exist before Perl 5.6.1.
+
+    if (eval { require File::Temp; 1 }) {
+        return File::Temp::tempfile("pnmquant_XXXX", 
+                                    SUFFIX=>".pnm", 
+                                    DIR=>File::Spec->tmpdir(),
+                                    UNLINK=>$TRUE);
+    } else {
+        my ($suffix) = @_;
+        my $fileName;
+        local *file;  # For some inexplicable reason, must be local, not my
+        my $i;
+        $i = 0;
+        do {
+            $fileName = File::Spec->tmpdir() . "/pnmquant_" . $i++ . $suffix;
+        } until sysopen(*file, $fileName, O_RDWR|O_CREAT|O_EXCL);
+
+        return(*file, $fileName);
+    }
 }
 
 
@@ -247,7 +273,7 @@ openSeekableAsStdin($cmdlineR->{infile});
 
 # Save Standard Output for our eventual output
 open(OLDOUT, ">&STDOUT");
-select(OLDOUT);  # avoids Perl bug where it says we never use STDOUT 
+select(OLDOUT);  # avoids Perl bug where it says we never use OLDOUT 
 
 
 my $mapfileSpec = makeColormap($cmdlineR->{ncolors},