diff --git a/ChangeLog b/ChangeLog
index f196b06..b7208e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2025-01-17  Jon Clayden  <code@clayden.org>
+
+	* src/littler.c: Set the LITTLER_SCRIPT_PATH environment variable to the
+	script's normalized path, when 'r' is used in a shebang line. This makes
+	the run-time path available to the script.
+
+	* configure.ac: Add check for realpath function used by the facility above
+
+	* configure: Idem
+
+	* src/config.h.in: Idem
+
+	* inst/man-page/r.1: Brief documentation of the LITTLER_SCRIPT_PATH
+	environment variable described above
+
 2024-11-01  Dirk Eddelbuettel  <edd@debian.org>
 
 	* DESCRIPTION (Date, Version): Roll micro version and date
diff --git a/configure b/configure
index 333c792..6ee7c9b 100755
--- a/configure
+++ b/configure
@@ -1,11 +1,11 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.71 for littler 0.3.20.
+# Generated by GNU Autoconf 2.72 for littler 0.3.20.
 #
 # Report bugs to <edd@debian.org>.
 #
 #
-# Copyright (C) 1992-1996, 1998-2017, 2020-2021 Free Software Foundation,
+# Copyright (C) 1992-1996, 1998-2017, 2020-2023 Free Software Foundation,
 # Inc.
 #
 #
@@ -17,7 +17,6 @@
 
 # Be more Bourne compatible
 DUALCASE=1; export DUALCASE # for MKS sh
-as_nop=:
 if test ${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
@@ -26,12 +25,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '${1+"$@"}'='"$@"'
   setopt NO_GLOB_SUBST
-else $as_nop
-  case `(set -o) 2>/dev/null` in #(
+else case e in #(
+  e) case `(set -o) 2>/dev/null` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 
@@ -103,7 +103,7 @@ IFS=$as_save_IFS
 
      ;;
 esac
-# We did not find ourselves, most probably we were run as `sh COMMAND'
+# We did not find ourselves, most probably we were run as 'sh COMMAND'
 # in which case we are not to be found in the path.
 if test "x$as_myself" = x; then
   as_myself=$0
@@ -133,15 +133,14 @@ case $- in # ((((
 esac
 exec $CONFIG_SHELL $as_opts "$as_myself" ${1+"$@"}
 # Admittedly, this is quite paranoid, since all the known shells bail
-# out after a failed `exec'.
+# out after a failed 'exec'.
 printf "%s\n" "$0: could not re-execute with $CONFIG_SHELL" >&2
 exit 255
   fi
   # We don't want this to propagate to other subprocesses.
           { _as_can_reexec=; unset _as_can_reexec;}
 if test "x$CONFIG_SHELL" = x; then
-  as_bourne_compatible="as_nop=:
-if test \${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
+  as_bourne_compatible="if test \${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
   NULLCMD=:
@@ -149,12 +148,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '\${1+\"\$@\"}'='\"\$@\"'
   setopt NO_GLOB_SUBST
-else \$as_nop
-  case \`(set -o) 2>/dev/null\` in #(
+else case e in #(
+  e) case \`(set -o) 2>/dev/null\` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 "
@@ -172,8 +172,9 @@ as_fn_ret_failure && { exitcode=1; echo as_fn_ret_failure succeeded.; }
 if ( set x; as_fn_ret_success y && test x = \"\$1\" )
 then :
 
-else \$as_nop
-  exitcode=1; echo positional parameters were not saved.
+else case e in #(
+  e) exitcode=1; echo positional parameters were not saved. ;;
+esac
 fi
 test x\$exitcode = x0 || exit 1
 blah=\$(echo \$(echo blah))
@@ -186,14 +187,15 @@ test -x / || exit 1"
   if (eval "$as_required") 2>/dev/null
 then :
   as_have_required=yes
-else $as_nop
-  as_have_required=no
+else case e in #(
+  e) as_have_required=no ;;
+esac
 fi
   if test x$as_have_required = xyes && (eval "$as_suggested") 2>/dev/null
 then :
 
-else $as_nop
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+else case e in #(
+  e) as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
 as_found=false
 for as_dir in /bin$PATH_SEPARATOR/usr/bin$PATH_SEPARATOR$PATH
 do
@@ -226,12 +228,13 @@ IFS=$as_save_IFS
 if $as_found
 then :
 
-else $as_nop
-  if { test -f "$SHELL" || test -f "$SHELL.exe"; } &&
+else case e in #(
+  e) if { test -f "$SHELL" || test -f "$SHELL.exe"; } &&
 	      as_run=a "$SHELL" -c "$as_bourne_compatible""$as_required" 2>/dev/null
 then :
   CONFIG_SHELL=$SHELL as_have_required=yes
-fi
+fi ;;
+esac
 fi
 
 
@@ -253,7 +256,7 @@ case $- in # ((((
 esac
 exec $CONFIG_SHELL $as_opts "$as_myself" ${1+"$@"}
 # Admittedly, this is quite paranoid, since all the known shells bail
-# out after a failed `exec'.
+# out after a failed 'exec'.
 printf "%s\n" "$0: could not re-execute with $CONFIG_SHELL" >&2
 exit 255
 fi
@@ -273,7 +276,8 @@ $0: manually run the script under such a shell if you do
 $0: have one."
   fi
   exit 1
-fi
+fi ;;
+esac
 fi
 fi
 SHELL=${CONFIG_SHELL-/bin/sh}
@@ -312,14 +316,6 @@ as_fn_exit ()
   as_fn_set_status $1
   exit $1
 } # as_fn_exit
-# as_fn_nop
-# ---------
-# Do nothing but, unlike ":", preserve the value of $?.
-as_fn_nop ()
-{
-  return $?
-}
-as_nop=as_fn_nop
 
 # as_fn_mkdir_p
 # -------------
@@ -388,11 +384,12 @@ then :
   {
     eval $1+=\$2
   }'
-else $as_nop
-  as_fn_append ()
+else case e in #(
+  e) as_fn_append ()
   {
     eval $1=\$$1\$2
-  }
+  } ;;
+esac
 fi # as_fn_append
 
 # as_fn_arith ARG...
@@ -406,21 +403,14 @@ then :
   {
     as_val=$(( $* ))
   }'
-else $as_nop
-  as_fn_arith ()
+else case e in #(
+  e) as_fn_arith ()
   {
     as_val=`expr "$@" || test $? -eq 1`
-  }
+  } ;;
+esac
 fi # as_fn_arith
 
-# as_fn_nop
-# ---------
-# Do nothing but, unlike ":", preserve the value of $?.
-as_fn_nop ()
-{
-  return $?
-}
-as_nop=as_fn_nop
 
 # as_fn_error STATUS ERROR [LINENO LOG_FD]
 # ----------------------------------------
@@ -494,6 +484,8 @@ as_cr_alnum=$as_cr_Letters$as_cr_digits
     /[$]LINENO/=
   ' <$as_myself |
     sed '
+      t clear
+      :clear
       s/[$]LINENO.*/&-/
       t lineno
       b
@@ -542,7 +534,6 @@ esac
 as_echo='printf %s\n'
 as_echo_n='printf %s'
 
-
 rm -f conf$$ conf$$.exe conf$$.file
 if test -d conf$$.dir; then
   rm -f conf$$.dir/conf$$.file
@@ -554,9 +545,9 @@ if (echo >conf$$.file) 2>/dev/null; then
   if ln -s conf$$.file conf$$ 2>/dev/null; then
     as_ln_s='ln -s'
     # ... but there are two gotchas:
-    # 1) On MSYS, both `ln -s file dir' and `ln file dir' fail.
-    # 2) DJGPP < 2.04 has no symlinks; `ln -s' creates a wrapper executable.
-    # In both cases, we have to default to `cp -pR'.
+    # 1) On MSYS, both 'ln -s file dir' and 'ln file dir' fail.
+    # 2) DJGPP < 2.04 has no symlinks; 'ln -s' creates a wrapper executable.
+    # In both cases, we have to default to 'cp -pR'.
     ln -s conf$$.file conf$$.dir 2>/dev/null && test ! -f conf$$.exe ||
       as_ln_s='cp -pR'
   elif ln conf$$.file conf$$ 2>/dev/null; then
@@ -581,10 +572,12 @@ as_test_x='test -x'
 as_executable_p=as_fn_executable_p
 
 # Sed expression to map a string onto a valid CPP name.
-as_tr_cpp="eval sed 'y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_cpp="y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g"
+as_tr_cpp="eval sed '$as_sed_cpp'" # deprecated
 
 # Sed expression to map a string onto a valid variable name.
-as_tr_sh="eval sed 'y%*+%pp%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_sh="y%*+%pp%;s%[^_$as_cr_alnum]%_%g"
+as_tr_sh="eval sed '$as_sed_sh'" # deprecated
 
 
 test -n "$DJDIR" || exec 7<&0 </dev/null
@@ -825,7 +818,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*disable-\(.*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid feature name: \`$ac_useropt'"
+      as_fn_error $? "invalid feature name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -851,7 +844,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*enable-\([^=]*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid feature name: \`$ac_useropt'"
+      as_fn_error $? "invalid feature name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1064,7 +1057,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*with-\([^=]*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid package name: \`$ac_useropt'"
+      as_fn_error $? "invalid package name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1080,7 +1073,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*without-\(.*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid package name: \`$ac_useropt'"
+      as_fn_error $? "invalid package name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1110,8 +1103,8 @@ do
   | --x-librar=* | --x-libra=* | --x-libr=* | --x-lib=* | --x-li=* | --x-l=*)
     x_libraries=$ac_optarg ;;
 
-  -*) as_fn_error $? "unrecognized option: \`$ac_option'
-Try \`$0 --help' for more information"
+  -*) as_fn_error $? "unrecognized option: '$ac_option'
+Try '$0 --help' for more information"
     ;;
 
   *=*)
@@ -1119,7 +1112,7 @@ Try \`$0 --help' for more information"
     # Reject names that are not valid shell variable names.
     case $ac_envvar in #(
       '' | [0-9]* | *[!_$as_cr_alnum]* )
-      as_fn_error $? "invalid variable name: \`$ac_envvar'" ;;
+      as_fn_error $? "invalid variable name: '$ac_envvar'" ;;
     esac
     eval $ac_envvar=\$ac_optarg
     export $ac_envvar ;;
@@ -1169,7 +1162,7 @@ do
   as_fn_error $? "expected an absolute directory name for --$ac_var: $ac_val"
 done
 
-# There might be people who depend on the old broken behavior: `$host'
+# There might be people who depend on the old broken behavior: '$host'
 # used to hold the argument of --host etc.
 # FIXME: To remove some day.
 build=$build_alias
@@ -1237,7 +1230,7 @@ if test ! -r "$srcdir/$ac_unique_file"; then
   test "$ac_srcdir_defaulted" = yes && srcdir="$ac_confdir or .."
   as_fn_error $? "cannot find sources ($ac_unique_file) in $srcdir"
 fi
-ac_msg="sources are in $srcdir, but \`cd $srcdir' does not work"
+ac_msg="sources are in $srcdir, but 'cd $srcdir' does not work"
 ac_abs_confdir=`(
 	cd "$srcdir" && test -r "./$ac_unique_file" || as_fn_error $? "$ac_msg"
 	pwd)`
@@ -1265,7 +1258,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures littler 0.3.20 to adapt to many kinds of systems.
+'configure' configures littler 0.3.20 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1279,11 +1272,11 @@ Configuration:
       --help=short        display options specific to this package
       --help=recursive    display the short help of all the included packages
   -V, --version           display version information and exit
-  -q, --quiet, --silent   do not print \`checking ...' messages
+  -q, --quiet, --silent   do not print 'checking ...' messages
       --cache-file=FILE   cache test results in FILE [disabled]
-  -C, --config-cache      alias for \`--cache-file=config.cache'
+  -C, --config-cache      alias for '--cache-file=config.cache'
   -n, --no-create         do not create output files
-      --srcdir=DIR        find the sources in DIR [configure dir or \`..']
+      --srcdir=DIR        find the sources in DIR [configure dir or '..']
 
 Installation directories:
   --prefix=PREFIX         install architecture-independent files in PREFIX
@@ -1291,10 +1284,10 @@ Installation directories:
   --exec-prefix=EPREFIX   install architecture-dependent files in EPREFIX
                           [PREFIX]
 
-By default, \`make install' will install all the files in
-\`$ac_default_prefix/bin', \`$ac_default_prefix/lib' etc.  You can specify
-an installation prefix other than \`$ac_default_prefix' using \`--prefix',
-for instance \`--prefix=\$HOME'.
+By default, 'make install' will install all the files in
+'$ac_default_prefix/bin', '$ac_default_prefix/lib' etc.  You can specify
+an installation prefix other than '$ac_default_prefix' using '--prefix',
+for instance '--prefix=\$HOME'.
 
 For better control, use the options below.
 
@@ -1345,7 +1338,7 @@ Some influential environment variables:
   CPPFLAGS    (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
               you have headers in a nonstandard directory <include dir>
 
-Use these variables to override the choices made by `configure' or to help
+Use these variables to override the choices made by 'configure' or to help
 it to find libraries and programs with nonstandard names/locations.
 
 Report bugs to <edd@debian.org>.
@@ -1413,9 +1406,9 @@ test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
 littler configure 0.3.20
-generated by GNU Autoconf 2.71
+generated by GNU Autoconf 2.72
 
-Copyright (C) 2021 Free Software Foundation, Inc.
+Copyright (C) 2023 Free Software Foundation, Inc.
 This configure script is free software; the Free Software Foundation
 gives unlimited permission to copy, distribute and modify it.
 _ACEOF
@@ -1454,11 +1447,12 @@ printf "%s\n" "$ac_try_echo"; } >&5
        } && test -s conftest.$ac_objext
 then :
   ac_retval=0
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_retval=1
+	ac_retval=1 ;;
+esac
 fi
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
   as_fn_set_status $ac_retval
@@ -1477,8 +1471,8 @@ printf %s "checking for $2... " >&6; }
 if eval test \${$3+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 $4
 #include <$2>
@@ -1486,10 +1480,12 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   eval "$3=yes"
-else $as_nop
-  eval "$3=no"
+else case e in #(
+  e) eval "$3=no" ;;
+esac
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
 eval ac_res=\$$3
 	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
@@ -1529,11 +1525,12 @@ printf "%s\n" "$ac_try_echo"; } >&5
        }
 then :
   ac_retval=0
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_retval=1
+	ac_retval=1 ;;
+esac
 fi
   # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
   # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
@@ -1556,15 +1553,15 @@ printf %s "checking for $2... " >&6; }
 if eval test \${$3+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 /* Define $2 to an innocuous variant, in case <limits.h> declares $2.
    For example, HP-UX 11i <limits.h> declares gettimeofday.  */
 #define $2 innocuous_$2
 
 /* System header to define __stub macros and hopefully few prototypes,
-   which can conflict with char $2 (); below.  */
+   which can conflict with char $2 (void); below.  */
 
 #include <limits.h>
 #undef $2
@@ -1575,7 +1572,7 @@ else $as_nop
 #ifdef __cplusplus
 extern "C"
 #endif
-char $2 ();
+char $2 (void);
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
     something starting with __ and the normal name is an alias.  */
@@ -1594,11 +1591,13 @@ _ACEOF
 if ac_fn_c_try_link "$LINENO"
 then :
   eval "$3=yes"
-else $as_nop
-  eval "$3=no"
+else case e in #(
+  e) eval "$3=no" ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
+    conftest$ac_exeext conftest.$ac_ext ;;
+esac
 fi
 eval ac_res=\$$3
 	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
@@ -1631,7 +1630,7 @@ This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
 It was created by littler $as_me 0.3.20, which was
-generated by GNU Autoconf 2.71.  Invocation command line was
+generated by GNU Autoconf 2.72.  Invocation command line was
 
   $ $0$ac_configure_args_raw
 
@@ -1877,10 +1876,10 @@ esac
 printf "%s\n" "$as_me: loading site script $ac_site_file" >&6;}
     sed 's/^/| /' "$ac_site_file" >&5
     . "$ac_site_file" \
-      || { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+      || { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "failed to load site script $ac_site_file
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; }
   fi
 done
 
@@ -1916,9 +1915,7 @@ struct stat;
 /* Most of the following tests are stolen from RCS 5.7 src/conf.sh.  */
 struct buf { int x; };
 struct buf * (*rcsopen) (struct buf *, struct stat *, int);
-static char *e (p, i)
-     char **p;
-     int i;
+static char *e (char **p, int i)
 {
   return p[i];
 }
@@ -1932,6 +1929,21 @@ static char *f (char * (*g) (char **, int), char **p, ...)
   return s;
 }
 
+/* C89 style stringification. */
+#define noexpand_stringify(a) #a
+const char *stringified = noexpand_stringify(arbitrary+token=sequence);
+
+/* C89 style token pasting.  Exercises some of the corner cases that
+   e.g. old MSVC gets wrong, but not very hard. */
+#define noexpand_concat(a,b) a##b
+#define expand_concat(a,b) noexpand_concat(a,b)
+extern int vA;
+extern int vbee;
+#define aye A
+#define bee B
+int *pvA = &expand_concat(v,aye);
+int *pvbee = &noexpand_concat(v,bee);
+
 /* OSF 4.0 Compaq cc is some sort of almost-ANSI by default.  It has
    function prototypes and stuff, but not \xHH hex character constants.
    These do not provoke an error unfortunately, instead are silently treated
@@ -1959,16 +1971,19 @@ ok |= (argc == 0 || f (e, argv, 0) != argv[0] || f (e, argv, 1) != argv[1]);
 
 # Test code for whether the C compiler supports C99 (global declarations)
 ac_c_conftest_c99_globals='
-// Does the compiler advertise C99 conformance?
+/* Does the compiler advertise C99 conformance? */
 #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 199901L
 # error "Compiler does not advertise C99 conformance"
 #endif
 
+// See if C++-style comments work.
+
 #include <stdbool.h>
 extern int puts (const char *);
 extern int printf (const char *, ...);
 extern int dprintf (int, const char *, ...);
 extern void *malloc (size_t);
+extern void free (void *);
 
 // Check varargs macros.  These examples are taken from C99 6.10.3.5.
 // dprintf is used instead of fprintf to avoid needing to declare
@@ -2018,7 +2033,6 @@ typedef const char *ccp;
 static inline int
 test_restrict (ccp restrict text)
 {
-  // See if C++-style comments work.
   // Iterate through items via the restricted pointer.
   // Also check for declarations in for loops.
   for (unsigned int i = 0; *(text+i) != '\''\0'\''; ++i)
@@ -2084,6 +2098,8 @@ ac_c_conftest_c99_main='
   ia->datasize = 10;
   for (int i = 0; i < ia->datasize; ++i)
     ia->data[i] = i * 1.234;
+  // Work around memory leak warnings.
+  free (ia);
 
   // Check named initializers.
   struct named_init ni = {
@@ -2105,7 +2121,7 @@ ac_c_conftest_c99_main='
 
 # Test code for whether the C compiler supports C11 (global declarations)
 ac_c_conftest_c11_globals='
-// Does the compiler advertise C11 conformance?
+/* Does the compiler advertise C11 conformance? */
 #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112L
 # error "Compiler does not advertise C11 conformance"
 #endif
@@ -2228,12 +2244,12 @@ for ac_var in $ac_precious_vars; do
   eval ac_new_val=\$ac_env_${ac_var}_value
   case $ac_old_set,$ac_new_set in
     set,)
-      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' was set to \`$ac_old_val' in the previous run" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' was set to \`$ac_old_val' in the previous run" >&2;}
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' was set to '$ac_old_val' in the previous run" >&5
+printf "%s\n" "$as_me: error: '$ac_var' was set to '$ac_old_val' in the previous run" >&2;}
       ac_cache_corrupted=: ;;
     ,set)
-      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' was not set in the previous run" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' was not set in the previous run" >&2;}
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' was not set in the previous run" >&5
+printf "%s\n" "$as_me: error: '$ac_var' was not set in the previous run" >&2;}
       ac_cache_corrupted=: ;;
     ,);;
     *)
@@ -2242,18 +2258,18 @@ printf "%s\n" "$as_me: error: \`$ac_var' was not set in the previous run" >&2;}
 	ac_old_val_w=`echo x $ac_old_val`
 	ac_new_val_w=`echo x $ac_new_val`
 	if test "$ac_old_val_w" != "$ac_new_val_w"; then
-	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' has changed since the previous run:" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' has changed since the previous run:" >&2;}
+	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' has changed since the previous run:" >&5
+printf "%s\n" "$as_me: error: '$ac_var' has changed since the previous run:" >&2;}
 	  ac_cache_corrupted=:
 	else
-	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: warning: ignoring whitespace changes in \`$ac_var' since the previous run:" >&5
-printf "%s\n" "$as_me: warning: ignoring whitespace changes in \`$ac_var' since the previous run:" >&2;}
+	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: warning: ignoring whitespace changes in '$ac_var' since the previous run:" >&5
+printf "%s\n" "$as_me: warning: ignoring whitespace changes in '$ac_var' since the previous run:" >&2;}
 	  eval $ac_var=\$ac_old_val
 	fi
-	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   former value:  \`$ac_old_val'" >&5
-printf "%s\n" "$as_me:   former value:  \`$ac_old_val'" >&2;}
-	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   current value: \`$ac_new_val'" >&5
-printf "%s\n" "$as_me:   current value: \`$ac_new_val'" >&2;}
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   former value:  '$ac_old_val'" >&5
+printf "%s\n" "$as_me:   former value:  '$ac_old_val'" >&2;}
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   current value: '$ac_new_val'" >&5
+printf "%s\n" "$as_me:   current value: '$ac_new_val'" >&2;}
       fi;;
   esac
   # Pass precious variables to config.status.
@@ -2269,11 +2285,11 @@ printf "%s\n" "$as_me:   current value: \`$ac_new_val'" >&2;}
   fi
 done
 if $ac_cache_corrupted; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: changes in the environment can compromise the build" >&5
 printf "%s\n" "$as_me: error: changes in the environment can compromise the build" >&2;}
-  as_fn_error $? "run \`${MAKE-make} distclean' and/or \`rm $cache_file'
+  as_fn_error $? "run '${MAKE-make} distclean' and/or 'rm $cache_file'
 	    and start over" "$LINENO" 5
 fi
 ## -------------------- ##
@@ -2332,8 +2348,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2355,7 +2371,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2377,8 +2394,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2400,7 +2417,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2435,8 +2453,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2458,7 +2476,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2480,8 +2499,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
   ac_prog_rejected=no
@@ -2520,7 +2539,8 @@ if test $ac_prog_rejected = yes; then
     ac_cv_prog_CC="$as_dir$ac_word${1+' '}$@"
   fi
 fi
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2544,8 +2564,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2567,7 +2587,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2593,8 +2614,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2616,7 +2637,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2654,8 +2676,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2677,7 +2699,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2699,8 +2722,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2722,7 +2745,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2751,10 +2775,10 @@ fi
 fi
 
 
-test -z "$CC" && { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+test -z "$CC" && { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "no acceptable C compiler found in \$PATH
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; }
 
 # Provide some information about the compiler.
 printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for C compiler version" >&5
@@ -2826,8 +2850,8 @@ printf "%s\n" "$ac_try_echo"; } >&5
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }
 then :
-  # Autoconf-2.13 could set the ac_cv_exeext variable to `no'.
-# So ignore a value of `no', otherwise this would lead to `EXEEXT = no'
+  # Autoconf-2.13 could set the ac_cv_exeext variable to 'no'.
+# So ignore a value of 'no', otherwise this would lead to 'EXEEXT = no'
 # in a Makefile.  We should not override ac_cv_exeext if it was cached,
 # so that the user can short-circuit this test for compilers unknown to
 # Autoconf.
@@ -2847,7 +2871,7 @@ do
 	   ac_cv_exeext=`expr "$ac_file" : '[^.]*\(\..*\)'`
 	fi
 	# We set ac_cv_exeext here because the later test for it is not
-	# safe: cross compilers may not add the suffix if given an `-o'
+	# safe: cross compilers may not add the suffix if given an '-o'
 	# argument, so we may need to know it at that point already.
 	# Even if this section looks crufty: it has the advantage of
 	# actually working.
@@ -2858,8 +2882,9 @@ do
 done
 test "$ac_cv_exeext" = no && ac_cv_exeext=
 
-else $as_nop
-  ac_file=''
+else case e in #(
+  e) ac_file='' ;;
+esac
 fi
 if test -z "$ac_file"
 then :
@@ -2868,13 +2893,14 @@ printf "%s\n" "no" >&6; }
 printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error 77 "C compiler cannot create executables
-See \`config.log' for more details" "$LINENO" 5; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-printf "%s\n" "yes" >&6; }
+See 'config.log' for more details" "$LINENO" 5; }
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; } ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for C compiler default output file name" >&5
 printf %s "checking for C compiler default output file name... " >&6; }
@@ -2898,10 +2924,10 @@ printf "%s\n" "$ac_try_echo"; } >&5
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }
 then :
-  # If both `conftest.exe' and `conftest' are `present' (well, observable)
-# catch `conftest.exe'.  For instance with Cygwin, `ls conftest' will
-# work properly (i.e., refer to `conftest.exe'), while it won't with
-# `rm'.
+  # If both 'conftest.exe' and 'conftest' are 'present' (well, observable)
+# catch 'conftest.exe'.  For instance with Cygwin, 'ls conftest' will
+# work properly (i.e., refer to 'conftest.exe'), while it won't with
+# 'rm'.
 for ac_file in conftest.exe conftest conftest.*; do
   test -f "$ac_file" || continue
   case $ac_file in
@@ -2911,11 +2937,12 @@ for ac_file in conftest.exe conftest conftest.*; do
     * ) break;;
   esac
 done
-else $as_nop
-  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+else case e in #(
+  e) { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "cannot compute suffix of executables: cannot compile and link
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; } ;;
+esac
 fi
 rm -f conftest conftest$ac_cv_exeext
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_exeext" >&5
@@ -2931,6 +2958,8 @@ int
 main (void)
 {
 FILE *f = fopen ("conftest.out", "w");
+ if (!f)
+  return 1;
  return ferror (f) || fclose (f) != 0;
 
   ;
@@ -2970,26 +2999,27 @@ printf "%s\n" "$ac_try_echo"; } >&5
     if test "$cross_compiling" = maybe; then
 	cross_compiling=yes
     else
-	{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+	{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error 77 "cannot run C compiled programs.
-If you meant to cross compile, use \`--host'.
-See \`config.log' for more details" "$LINENO" 5; }
+If you meant to cross compile, use '--host'.
+See 'config.log' for more details" "$LINENO" 5; }
     fi
   fi
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $cross_compiling" >&5
 printf "%s\n" "$cross_compiling" >&6; }
 
-rm -f conftest.$ac_ext conftest$ac_cv_exeext conftest.out
+rm -f conftest.$ac_ext conftest$ac_cv_exeext \
+  conftest.o conftest.obj conftest.out
 ac_clean_files=$ac_clean_files_save
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for suffix of object files" >&5
 printf %s "checking for suffix of object files... " >&6; }
 if test ${ac_cv_objext+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -3021,16 +3051,18 @@ then :
        break;;
   esac
 done
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "cannot compute suffix of object files: cannot compile
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; } ;;
+esac
 fi
-rm -f conftest.$ac_cv_objext conftest.$ac_ext
+rm -f conftest.$ac_cv_objext conftest.$ac_ext ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_objext" >&5
 printf "%s\n" "$ac_cv_objext" >&6; }
@@ -3041,8 +3073,8 @@ printf %s "checking whether the compiler supports GNU C... " >&6; }
 if test ${ac_cv_c_compiler_gnu+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -3059,12 +3091,14 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   ac_compiler_gnu=yes
-else $as_nop
-  ac_compiler_gnu=no
+else case e in #(
+  e) ac_compiler_gnu=no ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 ac_cv_c_compiler_gnu=$ac_compiler_gnu
-
+ ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_compiler_gnu" >&5
 printf "%s\n" "$ac_cv_c_compiler_gnu" >&6; }
@@ -3082,8 +3116,8 @@ printf %s "checking whether $CC accepts -g... " >&6; }
 if test ${ac_cv_prog_cc_g+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_save_c_werror_flag=$ac_c_werror_flag
+else case e in #(
+  e) ac_save_c_werror_flag=$ac_c_werror_flag
    ac_c_werror_flag=yes
    ac_cv_prog_cc_g=no
    CFLAGS="-g"
@@ -3101,8 +3135,8 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   ac_cv_prog_cc_g=yes
-else $as_nop
-  CFLAGS=""
+else case e in #(
+  e) CFLAGS=""
       cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -3117,8 +3151,8 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
 
-else $as_nop
-  ac_c_werror_flag=$ac_save_c_werror_flag
+else case e in #(
+  e) ac_c_werror_flag=$ac_save_c_werror_flag
 	 CFLAGS="-g"
 	 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3135,12 +3169,15 @@ if ac_fn_c_try_compile "$LINENO"
 then :
   ac_cv_prog_cc_g=yes
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-   ac_c_werror_flag=$ac_save_c_werror_flag
+   ac_c_werror_flag=$ac_save_c_werror_flag ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_g" >&5
 printf "%s\n" "$ac_cv_prog_cc_g" >&6; }
@@ -3167,8 +3204,8 @@ printf %s "checking for $CC option to enable C11 features... " >&6; }
 if test ${ac_cv_prog_cc_c11+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c11=no
+else case e in #(
+  e) ac_cv_prog_cc_c11=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3185,25 +3222,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c11" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c11" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c11" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c11" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c11" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c11" >&5
 printf "%s\n" "$ac_cv_prog_cc_c11" >&6; }
-     CC="$CC $ac_cv_prog_cc_c11"
+     CC="$CC $ac_cv_prog_cc_c11" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11
-  ac_prog_cc_stdc=c11
+  ac_prog_cc_stdc=c11 ;;
+esac
 fi
 fi
 if test x$ac_prog_cc_stdc = xno
@@ -3213,8 +3253,8 @@ printf %s "checking for $CC option to enable C99 features... " >&6; }
 if test ${ac_cv_prog_cc_c99+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c99=no
+else case e in #(
+  e) ac_cv_prog_cc_c99=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3231,25 +3271,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c99" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c99" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c99" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c99" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c99" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c99" >&5
 printf "%s\n" "$ac_cv_prog_cc_c99" >&6; }
-     CC="$CC $ac_cv_prog_cc_c99"
+     CC="$CC $ac_cv_prog_cc_c99" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99
-  ac_prog_cc_stdc=c99
+  ac_prog_cc_stdc=c99 ;;
+esac
 fi
 fi
 if test x$ac_prog_cc_stdc = xno
@@ -3259,8 +3302,8 @@ printf %s "checking for $CC option to enable C89 features... " >&6; }
 if test ${ac_cv_prog_cc_c89+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c89=no
+else case e in #(
+  e) ac_cv_prog_cc_c89=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3277,25 +3320,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c89" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c89" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c89" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c89" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c89" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c89" >&5
 printf "%s\n" "$ac_cv_prog_cc_c89" >&6; }
-     CC="$CC $ac_cv_prog_cc_c89"
+     CC="$CC $ac_cv_prog_cc_c89" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89
-  ac_prog_cc_stdc=c89
+  ac_prog_cc_stdc=c89 ;;
+esac
 fi
 fi
 
@@ -3345,8 +3391,9 @@ then :
 
 printf "%s\n" "#define HAVE_GETOPT_H 1" >>confdefs.h
 
-else $as_nop
-  as_fn_error $? "littler needs getopt support to run. Please find and install it." "$LINENO" 5
+else case e in #(
+  e) as_fn_error $? "littler needs getopt support to run. Please find and install it." "$LINENO" 5 ;;
+esac
 fi
 
 
@@ -3412,6 +3459,14 @@ printf "%s\n" "#define HAVE_TIME 1" >>confdefs.h
 
 fi
 
+ac_fn_c_check_func "$LINENO" "realpath" "ac_cv_func_realpath"
+if test "x$ac_cv_func_realpath" = xyes
+then :
+
+printf "%s\n" "#define HAVE_REALPATH 1" >>confdefs.h
+
+fi
+
 
 
 # Checks for typedefs, structures, and compiler characteristics.
@@ -3504,8 +3559,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_path_NAMETOOL+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  case $NAMETOOL in
+else case e in #(
+  e) case $NAMETOOL in
   [\\/]* | ?:[\\/]*)
   ac_cv_path_NAMETOOL="$NAMETOOL" # Let the user override the test with a path.
   ;;
@@ -3530,6 +3585,7 @@ done
 IFS=$as_save_IFS
 
   ;;
+esac ;;
 esac
 fi
 NAMETOOL=$ac_cv_path_NAMETOOL
@@ -3572,8 +3628,8 @@ cat >confcache <<\_ACEOF
 # config.status only pays attention to the cache file if you give it
 # the --recheck option to rerun configure.
 #
-# `ac_cv_env_foo' variables (set or unset) will be overridden when
-# loading this file, other *unset* `ac_cv_foo' will be assigned the
+# 'ac_cv_env_foo' variables (set or unset) will be overridden when
+# loading this file, other *unset* 'ac_cv_foo' will be assigned the
 # following values.
 
 _ACEOF
@@ -3603,14 +3659,14 @@ printf "%s\n" "$as_me: WARNING: cache variable $ac_var contains a newline" >&2;}
   (set) 2>&1 |
     case $as_nl`(ac_space=' '; set) 2>&1` in #(
     *${as_nl}ac_space=\ *)
-      # `set' does not quote correctly, so add quotes: double-quote
+      # 'set' does not quote correctly, so add quotes: double-quote
       # substitution turns \\\\ into \\, and sed turns \\ into \.
       sed -n \
 	"s/'/'\\\\''/g;
 	  s/^\\([_$as_cr_alnum]*_cv_[_$as_cr_alnum]*\\)=\\(.*\\)/\\1='\\2'/p"
       ;; #(
     *)
-      # `set' quotes correctly as required by POSIX, so do not add quotes.
+      # 'set' quotes correctly as required by POSIX, so do not add quotes.
       sed -n "/^[_$as_cr_alnum]*_cv_[_$as_cr_alnum]*=/p"
       ;;
     esac |
@@ -3700,7 +3756,6 @@ cat >>$CONFIG_STATUS <<\_ASEOF || as_write_fail=1
 
 # Be more Bourne compatible
 DUALCASE=1; export DUALCASE # for MKS sh
-as_nop=:
 if test ${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
@@ -3709,12 +3764,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '${1+"$@"}'='"$@"'
   setopt NO_GLOB_SUBST
-else $as_nop
-  case `(set -o) 2>/dev/null` in #(
+else case e in #(
+  e) case `(set -o) 2>/dev/null` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 
@@ -3786,7 +3842,7 @@ IFS=$as_save_IFS
 
      ;;
 esac
-# We did not find ourselves, most probably we were run as `sh COMMAND'
+# We did not find ourselves, most probably we were run as 'sh COMMAND'
 # in which case we are not to be found in the path.
 if test "x$as_myself" = x; then
   as_myself=$0
@@ -3815,7 +3871,6 @@ as_fn_error ()
 } # as_fn_error
 
 
-
 # as_fn_set_status STATUS
 # -----------------------
 # Set $? to STATUS, without forking.
@@ -3855,11 +3910,12 @@ then :
   {
     eval $1+=\$2
   }'
-else $as_nop
-  as_fn_append ()
+else case e in #(
+  e) as_fn_append ()
   {
     eval $1=\$$1\$2
-  }
+  } ;;
+esac
 fi # as_fn_append
 
 # as_fn_arith ARG...
@@ -3873,11 +3929,12 @@ then :
   {
     as_val=$(( $* ))
   }'
-else $as_nop
-  as_fn_arith ()
+else case e in #(
+  e) as_fn_arith ()
   {
     as_val=`expr "$@" || test $? -eq 1`
-  }
+  } ;;
+esac
 fi # as_fn_arith
 
 
@@ -3960,9 +4017,9 @@ if (echo >conf$$.file) 2>/dev/null; then
   if ln -s conf$$.file conf$$ 2>/dev/null; then
     as_ln_s='ln -s'
     # ... but there are two gotchas:
-    # 1) On MSYS, both `ln -s file dir' and `ln file dir' fail.
-    # 2) DJGPP < 2.04 has no symlinks; `ln -s' creates a wrapper executable.
-    # In both cases, we have to default to `cp -pR'.
+    # 1) On MSYS, both 'ln -s file dir' and 'ln file dir' fail.
+    # 2) DJGPP < 2.04 has no symlinks; 'ln -s' creates a wrapper executable.
+    # In both cases, we have to default to 'cp -pR'.
     ln -s conf$$.file conf$$.dir 2>/dev/null && test ! -f conf$$.exe ||
       as_ln_s='cp -pR'
   elif ln conf$$.file conf$$ 2>/dev/null; then
@@ -4043,10 +4100,12 @@ as_test_x='test -x'
 as_executable_p=as_fn_executable_p
 
 # Sed expression to map a string onto a valid CPP name.
-as_tr_cpp="eval sed 'y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_cpp="y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g"
+as_tr_cpp="eval sed '$as_sed_cpp'" # deprecated
 
 # Sed expression to map a string onto a valid variable name.
-as_tr_sh="eval sed 'y%*+%pp%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_sh="y%*+%pp%;s%[^_$as_cr_alnum]%_%g"
+as_tr_sh="eval sed '$as_sed_sh'" # deprecated
 
 
 exec 6>&1
@@ -4062,7 +4121,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # values after options handling.
 ac_log="
 This file was extended by littler $as_me 0.3.20, which was
-generated by GNU Autoconf 2.71.  Invocation command line was
+generated by GNU Autoconf 2.72.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
   CONFIG_HEADERS  = $CONFIG_HEADERS
@@ -4093,7 +4152,7 @@ _ACEOF
 
 cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 ac_cs_usage="\
-\`$as_me' instantiates files and other configuration actions
+'$as_me' instantiates files and other configuration actions
 from templates according to the current configuration.  Unless the files
 and actions are specified as TAGs, all are instantiated by default.
 
@@ -4126,10 +4185,10 @@ cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config='$ac_cs_config_escaped'
 ac_cs_version="\\
 littler config.status 0.3.20
-configured by $0, generated by GNU Autoconf 2.71,
+configured by $0, generated by GNU Autoconf 2.72,
   with options \\"\$ac_cs_config\\"
 
-Copyright (C) 2021 Free Software Foundation, Inc.
+Copyright (C) 2023 Free Software Foundation, Inc.
 This config.status script is free software; the Free Software Foundation
 gives unlimited permission to copy, distribute and modify it."
 
@@ -4188,8 +4247,8 @@ do
     ac_need_defaults=false;;
   --he | --h)
     # Conflict between --help and --header
-    as_fn_error $? "ambiguous option: \`$1'
-Try \`$0 --help' for more information.";;
+    as_fn_error $? "ambiguous option: '$1'
+Try '$0 --help' for more information.";;
   --help | --hel | -h )
     printf "%s\n" "$ac_cs_usage"; exit ;;
   -q | -quiet | --quiet | --quie | --qui | --qu | --q \
@@ -4197,8 +4256,8 @@ Try \`$0 --help' for more information.";;
     ac_cs_silent=: ;;
 
   # This is an error.
-  -*) as_fn_error $? "unrecognized option: \`$1'
-Try \`$0 --help' for more information." ;;
+  -*) as_fn_error $? "unrecognized option: '$1'
+Try '$0 --help' for more information." ;;
 
   *) as_fn_append ac_config_targets " $1"
      ac_need_defaults=false ;;
@@ -4250,7 +4309,7 @@ do
     "src/Makevars") CONFIG_FILES="$CONFIG_FILES src/Makevars" ;;
     "src/gitversion.h") CONFIG_FILES="$CONFIG_FILES src/gitversion.h" ;;
 
-  *) as_fn_error $? "invalid argument: \`$ac_config_target'" "$LINENO" 5;;
+  *) as_fn_error $? "invalid argument: '$ac_config_target'" "$LINENO" 5;;
   esac
 done
 
@@ -4269,7 +4328,7 @@ fi
 # creating and moving files from /tmp can sometimes cause problems.
 # Hook for its removal unless debugging.
 # Note that there is a small window in which the directory will not be cleaned:
-# after its creation but before its name has been assigned to `$tmp'.
+# after its creation but before its name has been assigned to '$tmp'.
 $debug ||
 {
   tmp= ac_tmp=
@@ -4293,7 +4352,7 @@ ac_tmp=$tmp
 
 # Set up the scripts for CONFIG_FILES section.
 # No need to generate them if there are no CONFIG_FILES.
-# This happens for instance with `./config.status config.h'.
+# This happens for instance with './config.status config.h'.
 if test -n "$CONFIG_FILES"; then
 
 
@@ -4451,13 +4510,13 @@ fi # test -n "$CONFIG_FILES"
 
 # Set up the scripts for CONFIG_HEADERS section.
 # No need to generate them if there are no CONFIG_HEADERS.
-# This happens for instance with `./config.status Makefile'.
+# This happens for instance with './config.status Makefile'.
 if test -n "$CONFIG_HEADERS"; then
 cat >"$ac_tmp/defines.awk" <<\_ACAWK ||
 BEGIN {
 _ACEOF
 
-# Transform confdefs.h into an awk script `defines.awk', embedded as
+# Transform confdefs.h into an awk script 'defines.awk', embedded as
 # here-document in config.status, that substitutes the proper values into
 # config.h.in to produce config.h.
 
@@ -4567,7 +4626,7 @@ do
   esac
   case $ac_mode$ac_tag in
   :[FHL]*:*);;
-  :L* | :C*:*) as_fn_error $? "invalid tag \`$ac_tag'" "$LINENO" 5;;
+  :L* | :C*:*) as_fn_error $? "invalid tag '$ac_tag'" "$LINENO" 5;;
   :[FH]-) ac_tag=-:-;;
   :[FH]*) ac_tag=$ac_tag:$ac_tag.in;;
   esac
@@ -4589,19 +4648,19 @@ do
       -) ac_f="$ac_tmp/stdin";;
       *) # Look for the file first in the build tree, then in the source tree
 	 # (if the path is not absolute).  The absolute path cannot be DOS-style,
-	 # because $ac_f cannot contain `:'.
+	 # because $ac_f cannot contain ':'.
 	 test -f "$ac_f" ||
 	   case $ac_f in
 	   [\\/$]*) false;;
 	   *) test -f "$srcdir/$ac_f" && ac_f="$srcdir/$ac_f";;
 	   esac ||
-	   as_fn_error 1 "cannot find input file: \`$ac_f'" "$LINENO" 5;;
+	   as_fn_error 1 "cannot find input file: '$ac_f'" "$LINENO" 5;;
       esac
       case $ac_f in *\'*) ac_f=`printf "%s\n" "$ac_f" | sed "s/'/'\\\\\\\\''/g"`;; esac
       as_fn_append ac_file_inputs " '$ac_f'"
     done
 
-    # Let's still pretend it is `configure' which instantiates (i.e., don't
+    # Let's still pretend it is 'configure' which instantiates (i.e., don't
     # use $as_me), people would be surprised to read:
     #    /* config.h.  Generated by config.status.  */
     configure_input='Generated from '`
@@ -4725,7 +4784,7 @@ cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 esac
 _ACEOF
 
-# Neutralize VPATH when `$srcdir' = `.'.
+# Neutralize VPATH when '$srcdir' = '.'.
 # Shell code in configure.ac might set extrasub.
 # FIXME: do we really want to maintain this feature?
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
@@ -4754,9 +4813,9 @@ test -z "$ac_datarootdir_hack$ac_datarootdir_seen" &&
   { ac_out=`sed -n '/\${datarootdir}/p' "$ac_tmp/out"`; test -n "$ac_out"; } &&
   { ac_out=`sed -n '/^[	 ]*datarootdir[	 ]*:*=/p' \
       "$ac_tmp/out"`; test -z "$ac_out"; } &&
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: $ac_file contains a reference to the variable \`datarootdir'
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: $ac_file contains a reference to the variable 'datarootdir'
 which seems to be undefined.  Please make sure it is defined" >&5
-printf "%s\n" "$as_me: WARNING: $ac_file contains a reference to the variable \`datarootdir'
+printf "%s\n" "$as_me: WARNING: $ac_file contains a reference to the variable 'datarootdir'
 which seems to be undefined.  Please make sure it is defined" >&2;}
 
   rm -f "$ac_tmp/stdin"
diff --git a/configure.ac b/configure.ac
index d35c205..78c8f42 100644
--- a/configure.ac
+++ b/configure.ac
@@ -59,6 +59,7 @@ AC_CHECK_FUNC(clock_gettime,AC_DEFINE(HAVE_CLOCK_GETTIME,1,[Define if you have c
 AC_CHECK_FUNC(realtime,AC_DEFINE(HAVE_REALTIME,1,[Define if you have realtime.]))
 AC_CHECK_FUNC(gettimeofday,AC_DEFINE(HAVE_GETTIMEOFDAY,1,[Define if you have the gettimeofday function.]))
 AC_CHECK_FUNC(time,AC_DEFINE(HAVE_TIME,1,[Define if you have the time function.]))
+AC_CHECK_FUNC(realpath,AC_DEFINE(HAVE_REALPATH,1,[Define if you have the realpath function.]))
 
 
 # Checks for typedefs, structures, and compiler characteristics.
diff --git a/inst/man-page/r.1 b/inst/man-page/r.1
index d837985..c817077 100644
--- a/inst/man-page/r.1
+++ b/inst/man-page/r.1
@@ -87,6 +87,9 @@ Evaluate 'expr' in R.
 .SH USAGE
 \fBr\fR can be used in command-line 'pipes' as well as in 'shebang'-style
 scripts.
+.SH ENVIRONMENT
+When used with a shebang line in a script file, the path to that file is made
+available to \fBR\fP in the \fBLITTLER_SCRIPT_PATH\fP environment variable.
 .SH EXAMPLES
 Piping \fBR\fP commands:
 
diff --git a/src/config.h.in b/src/config.h.in
index 263b885..d2e6d45 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -18,6 +18,9 @@
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H
 
+/* Define if you have the realpath function. */
+#undef HAVE_REALPATH
+
 /* Define if you have the setenv function. */
 #undef HAVE_SETENV
 
diff --git a/src/littler.c b/src/littler.c
index a1f4bd8..8922d4e 100644
--- a/src/littler.c
+++ b/src/littler.c
@@ -738,6 +738,17 @@ int main(int argc, char **argv){
         exit_val = parse_eval(&pb, evalstr, 1, verbose);
         destroy_membuf(pb);
     } else if (optind < argc && (strcmp(argv[optind],"-") != 0)) {
+        /* set environment variable giving path to script file */
+#if defined(HAVE_REALPATH) && defined(PATH_MAX)
+        char script_path[PATH_MAX + 1];
+        if (realpath(argv[optind], script_path) != NULL)
+            setenv("LITTLER_SCRIPT_PATH", script_path, 1);
+        else
+            setenv("LITTLER_SCRIPT_PATH", argv[optind], 1);
+#else
+        setenv("LITTLER_SCRIPT_PATH", argv[optind], 1);
+#endif
+
         /* call R function source(filename) */
         exit_val = source(argv[optind]);
     } else {