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

8 files changed, 184 insertions, 12 deletions

diff --git a/doc/HISTORY b/doc/HISTORY
index d7c6a421..573fc721 100644
--- a/doc/HISTORY
+++ b/doc/HISTORY
@@ -6,6 +6,9 @@ CHANGE HISTORY
 
 not yet  BJH  Release 10.63.00
 
+              Perl programs: make them shell programs that reinvoke themselves
+              as perl so we can get the Perl interpreter from the PATH.
+
               pnmpsnr: fix bug: says types aren't the same when they are.
               Introduced in 10.61 (December 2012).
               
diff --git a/editor/pnmflip b/editor/pnmflip
index 44d95b45..07d4ddb9 100755
--- a/editor/pnmflip
+++ b/editor/pnmflip
@@ -1,5 +1,28 @@
-#!/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
 #============================================================================
 #  This is a compatibility interface to Pamflip.
 #
diff --git a/editor/pnmquant b/editor/pnmquant
index ae461a3d..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.
diff --git a/editor/pnmquantall b/editor/pnmquantall
index b7bb03d7..0890383e 100755
--- a/editor/pnmquantall
+++ b/editor/pnmquantall
@@ -1,3 +1,27 @@
+#!/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
 ##############################################################################
 #                                  pnmquantall  
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;
diff --git a/editor/ppmquant b/editor/ppmquant
index 08f4c187..57963982 100755
--- a/editor/ppmquant
+++ b/editor/ppmquant
@@ -1,4 +1,28 @@
-#!/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
 ##############################################################################
 #  This is nothing but a compatibility interface for Pnmquant.
 #  An old program coded to call Ppmquant will continue working because
diff --git a/editor/ppmshadow b/editor/ppmshadow
index 2a32fca0..62cdf8b8 100755
--- a/editor/ppmshadow
+++ b/editor/ppmshadow
@@ -1,15 +1,40 @@
-#!/usr/bin/perl -w
+#!/bin/sh
 
-#                         P P M S H A D O W
+##############################################################################
+# 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
+##############################################################################
+#                              ppmshadow
+##############################################################################
+#
 #            by John Walker  --  http://www.fourmilab.ch/
 #                          version = 1.2;
 #   --> with minor changes by Bryan Henderson to adapt to Netbpm.  
 #   See above web site for the real John Walker work, named pnmshadow.
-
+#
 #   Bryan Henderson later made some major style changes (use strict, etc) and
 #   eliminated most use of shells.  See Netbpm HISTORY file.
-
+#
 #   Pnmshadow is a brutal sledgehammer implemented in Perl which
 #   adds attractive shadows to images, as often seen in titles
 #   of World-Wide Web pages.  This program does not actually
@@ -20,7 +45,7 @@
 #
 #               This program is in the public domain.
 #
-#
+##############################################################################
 
 use strict;
 require 5.0;
diff --git a/generator/ppmrainbow b/generator/ppmrainbow
index 96e304ac..c0568d9b 100755
--- a/generator/ppmrainbow
+++ b/generator/ppmrainbow
@@ -1,4 +1,28 @@
-#!/usr/bin/perl -wl
+#!/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
 use strict;
 use Getopt::Long;