* configure: Defend against legacy, non-POSIX /bin/sh implementations.

We boostrap using #!/bin/sh, but try to detect a better shell
and re-execute the script with that shell. Furthermore, we now
set up the SHELL variable in config.make, so that make uses that
shell for executing build recipes.

1 files changed, 21 insertions, 0 deletions

diff --git a/configure b/configure
index 09581b9d..c1b80c34 100755
--- a/configure
+++ b/configure
@@ -31,6 +31,20 @@
 # in the arguments, oops.
 #
 
+if test x$txr_shell = x ; then
+  for shell in /usr/xpg4/bin/sh /bin/bash /usr/bin/bash ; do
+    if test -e $shell ; then
+       txr_shell=$shell
+    fi
+  done
+  if test x$txr_shell = x ; then
+    echo "No known POSIX shell found: falling back on /bin/sh, which may not work"
+    txr_shell=/bin/sh
+  fi
+  export txr_shell
+  exec $txr_shell $0 ${@+"$@"}
+fi
+
 set -u
 
 cmdline=
@@ -410,6 +424,8 @@ printf "+%s+\n|%s|\n+%s+\n" $banner_box "$banner_text" $banner_box
 
 set -e
 
+printf "We are using this shell: %s\n" $txr_shell
+
 #
 # Check for GNU make
 #
@@ -539,6 +555,11 @@ gen_config_make()
 # Changes to this file are lost when the above is re-run.
 #
 
+# Shell used by make for running recipes; this
+# is the as the shell we chose for the configure script,
+# derived from the txr_shell variable.
+SHELL := $txr_shell
+
 # absolute path to source code directory
 top_srcdir := $top_srcdir