diff --git a/classes/install.yaml b/classes/install.yaml
index e24ff758..fd26e6e9 100644
--- a/classes/install.yaml
+++ b/classes/install.yaml
@@ -163,23 +163,34 @@ packageSetup: |
         fi
     }
 
-    # replace absolute interpreter paths with /usr/bin/env <interpreter>
+    # Replace absolute interpreter paths with "/usr/bin/env <interpreter>" for
+    # all executable scripts in directory.
+    #
+    # $1: directory (optional, defaults to ".")
     installFixShebang()
     {
-        local f old new
+        local shebang
         while IFS= read -r -d $'\0' f; do
-            if cmp -s -n2 "$f" <<<'#!' ; then
-                read -r old_cmd old_arg < "$f"
-                if [[ "$old_cmd" == "#!/usr/bin/env" ]]; then
-                    continue
+            read -n 4096 -r shebang < "$f"
+            if [[ "${shebang:0:2}" == "#!" ]] ; then
+                # Match part after "#!". Tabs and spaces before and after the
+                # command are stripped by the kernel. We need to do the same!
+                if [[ "${shebang:2}" =~ ^[$' \t']*([$'^ \t']+)[$' \t']*(.*)$ ]] ; then
+                    case "${BASH_REMATCH[1]}" in
+                        /usr/bin/env | /bin/sh | /bin/bash)
+                            continue
+                            ;;
+                    esac
+
+                    local cmd="${BASH_REMATCH[1]##*/}"
+                    local arg="${BASH_REMATCH[2]}"
+                    new="#!/usr/bin/env ${arg:+-S }${cmd}${arg:+ ${arg@Q}}"
+                    sed -i -e "1c $new" "$f"
                 else
-                    old_cmd="${old_cmd:2}"
-                    old_cmd="${old_cmd##*/}"
+                    echo "WARNING: unrecognized shebang: $shebang"
                 fi
-                new="#!/usr/bin/env ${old_arg:+-S }${old_cmd}${old_arg:+ ${old_arg@Q}}"
-                sed -i -e "1c $new" "$f"
             fi
-       done < <(find "${1:-.}" -type f -perm -/111 -print0)
+       done < <(find "${1:-.}" -type f -perm /111 -print0)
     }
 
     # Everything except shared or static libraries or header files.
diff --git a/recipes/devel/autoconf-2.69.yaml b/recipes/devel/autoconf-2.69.yaml
index 392a7700..f6b6805d 100644
--- a/recipes/devel/autoconf-2.69.yaml
+++ b/recipes/devel/autoconf-2.69.yaml
@@ -11,7 +11,7 @@ checkoutSCM:
 
 checkoutDeterministic: True
 checkoutScript: |
-    patchApplySeries $<<autoconf-2.69/*.patch>>
+    patchApplySeries $<@autoconf-2.69/*.patch@>
     # We patch some files that would trigger the rebuild of the manpages.
     # Prevent that...
     touch man/*.1
diff --git a/recipes/devel/autoconf-2.69/0003-remove-abs-perl-path.patch b/recipes/devel/autoconf-2.69/0003-remove-abs-perl-path.patch
new file mode 100644
index 00000000..d04e115c
--- /dev/null
+++ b/recipes/devel/autoconf-2.69/0003-remove-abs-perl-path.patch
@@ -0,0 +1,86 @@
+From: Jan Kloetzke <jan@kloetzke.net>
+Subject: [PATCH] Remove absolute perl path
+
+The variaous autoconf scipts contain the trick that let's them execute
+even if they are interpreted by the shell. This line has the full path
+to perl which will not be correct in Bobs environment. As it is
+unneeded in the first place, just remove it.
+
+diff -Nurp a/bin/autoheader.in b/bin/autoheader.in
+--- a/bin/autoheader.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/autoheader.in	2025-09-12 15:53:30.661992545 +0200
+@@ -2,9 +2,6 @@
+ # -*- Perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autoheader -- create `config.h.in' from `configure.ac'
+ 
+ # Copyright (C) 1992-1994, 1996, 1998-2012 Free Software Foundation,
+diff -Nurp a/bin/autom4te.in b/bin/autom4te.in
+--- a/bin/autom4te.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/autom4te.in	2025-09-12 15:53:30.753996376 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autom4te - Wrapper around M4 libraries.
+ # Copyright (C) 2001-2003, 2005-2012 Free Software Foundation, Inc.
+ 
+diff -Nurp a/bin/autoreconf.in b/bin/autoreconf.in
+--- a/bin/autoreconf.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/autoreconf.in	2025-09-12 15:53:30.850000372 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autoreconf - install the GNU Build System in a directory tree
+ # Copyright (C) 1994, 1999-2012 Free Software Foundation, Inc.
+ 
+diff -Nurp a/bin/autoscan.in b/bin/autoscan.in
+--- a/bin/autoscan.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/autoscan.in	2025-09-12 15:53:30.934003871 +0200
+@@ -20,9 +20,6 @@
+ 
+ # Written by David MacKenzie <djm@gnu.ai.mit.edu>.
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ BEGIN
+ {
+   use File::Basename;
+diff -Nurp a/bin/autoupdate.in b/bin/autoupdate.in
+--- a/bin/autoupdate.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/autoupdate.in	2025-09-12 15:53:31.026007701 +0200
+@@ -21,9 +21,6 @@
+ # Originally written by David MacKenzie <djm@gnu.ai.mit.edu>.
+ # Rewritten by Akim Demaille <akim@freefriends.org>.
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ BEGIN
+ {
+   use File::Basename;
+diff -Nurp a/bin/ifnames.in b/bin/ifnames.in
+--- a/bin/ifnames.in	2025-09-12 15:51:09.408126785 +0200
++++ b/bin/ifnames.in	2025-09-12 15:53:31.074009699 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # ifnames - print the identifiers used in C preprocessor conditionals
+ 
+ # Copyright (C) 1994-1995, 1999-2003, 2005-2012 Free Software
diff --git a/recipes/devel/autoconf/0003-remove-abs-perl-path.patch b/recipes/devel/autoconf/0003-remove-abs-perl-path.patch
new file mode 100644
index 00000000..69c9de85
--- /dev/null
+++ b/recipes/devel/autoconf/0003-remove-abs-perl-path.patch
@@ -0,0 +1,99 @@
+From: Jan Kloetzke <jan@kloetzke.net>
+Subject: [PATCH] Remove absolute perl path
+
+The variaous autoconf scipts contain the trick that let's them execute
+even if they are interpreted by the shell. This line has the full path
+to perl which will not be correct in Bobs environment. As it is
+unneeded in the first place, just remove it.
+
+diff -Nurp a/bin/autoconf.in b/bin/autoconf.in
+--- a/bin/autoconf.in	2025-09-12 11:22:28.208013268 +0200
++++ b/bin/autoconf.in	2025-09-12 15:37:32.333735416 +0200
+@@ -2,9 +2,6 @@
+ # -*- Perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autoconf -- create 'configure' using m4 macros.
+ 
+ # Copyright (C) 1992-1994, 1996, 1999-2017, 2020-2023 Free Software
+diff -Nurp a/bin/autoheader.in b/bin/autoheader.in
+--- a/bin/autoheader.in	2025-09-12 11:22:28.208013268 +0200
++++ b/bin/autoheader.in	2025-09-12 15:37:35.989891503 +0200
+@@ -2,9 +2,6 @@
+ # -*- Perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autoheader -- create 'config.h.in' from 'configure.ac'.
+ 
+ # Copyright (C) 1992-1994, 1996, 1998-2017, 2020-2023 Free Software
+diff -Nurp a/bin/autom4te.in b/bin/autom4te.in
+--- a/bin/autom4te.in	2025-09-12 11:22:28.212013444 +0200
++++ b/bin/autom4te.in	2025-09-12 15:37:39.382036313 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autom4te - Wrapper around M4 libraries.
+ # Copyright (C) 2001-2003, 2005-2017, 2020-2023 Free Software
+ # Foundation, Inc.
+diff -Nurp a/bin/autoreconf.in b/bin/autoreconf.in
+--- a/bin/autoreconf.in	2025-09-12 11:22:28.212013444 +0200
++++ b/bin/autoreconf.in	2025-09-12 15:37:44.074236624 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # autoreconf - install the GNU Build System in a directory tree
+ # Copyright (C) 1994, 1999-2017, 2020-2023 Free Software Foundation,
+ # Inc.
+diff -Nurp a/bin/autoscan.in b/bin/autoscan.in
+--- a/bin/autoscan.in	2025-09-12 11:22:28.212013444 +0200
++++ b/bin/autoscan.in	2025-09-12 15:38:05.559153749 +0200
+@@ -21,9 +21,6 @@
+ 
+ # Written by David MacKenzie <djm@gnu.ai.mit.edu>.
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ use 5.006;
+ use strict;
+ use warnings FATAL => 'all';
+diff -Nurp a/bin/autoupdate.in b/bin/autoupdate.in
+--- a/bin/autoupdate.in	2025-09-12 11:22:28.212013444 +0200
++++ b/bin/autoupdate.in	2025-09-12 15:38:05.683159042 +0200
+@@ -22,9 +22,6 @@
+ # Originally written by David MacKenzie <djm@gnu.ai.mit.edu>.
+ # Rewritten by Akim Demaille <akim@freefriends.org>.
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ use 5.006;
+ use strict;
+ use warnings FATAL => 'all';
+diff -Nurp a/bin/ifnames.in b/bin/ifnames.in
+--- a/bin/ifnames.in	2025-09-12 11:22:28.212013444 +0200
++++ b/bin/ifnames.in	2025-09-12 15:38:05.735161261 +0200
+@@ -2,9 +2,6 @@
+ # -*- perl -*-
+ # @configure_input@
+ 
+-eval 'case $# in 0) exec @PERL@ -S "$0";; *) exec @PERL@ -S "$0" "$@";; esac'
+-    if 0;
+-
+ # ifnames - print the identifiers used in C preprocessor conditionals
+ 
+ # Copyright (C) 1994-1995, 1999-2003, 2005-2017, 2020-2023 Free Software