Index: lib/configure
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 CONFIG="config.mk"
 PREFIX="/usr/local"
@@ -105,7 +105,7 @@
 
 # If someone runs sudo make install as very first command, and configure later,
 # $CONFIG cannot be overwritten, and must be deleted before continuing.
-if [[ -f "$CONFIG" && ! -w "$CONFIG" ]]; then
+if [ -f "$CONFIG" -a ! -w "$CONFIG" ]; then
     echo "Cannot overwrite file $CONFIG! Please delete it."
     exit 1
 fi
@@ -167,12 +167,8 @@
 # SSE
 if [ "$SSE" = 'auto' ]; then
     SSE=0
-    if type uname > /dev/null; then
-        if [[ "$(uname -m)" =~ "amd64" || "$(uname -m)" =~ "x86_64" ||
-              "$(grep -E -m1 "^flags" /proc/cpuinfo)" =~ "sse" ]]; then
-            SSE=1
-        fi
-    fi
+    echo $(uname -m) | grep -E -q '(amd|x86_)64' && SSE=1
+    grep -E -m1 -q '^flags.*sse' /proc/cpuinfo 2>/dev/null && SSE=1
 fi
 
 if [ "$SSE" -eq 1 ]; then
@@ -195,9 +191,8 @@
     else
         OPENMPFLAGS="-fopenmp"
     fi
-    if [[ "$("$CC" -xc -E $OPENMPFLAGS <(echo "#ifdef _OPENMP
-           #include <omp.h>
-           #endif") 2>&1)" =~ "omp_get_thread_num" ]]; then
+    if echo "$(printf '#ifdef _OPENMP\n#include <omp.h>\n#endif\n' | \
+        "$CC" -xc -E $OPENMPFLAGS - 2>&1)" | grep -q omp_get_thread_num; then
         cflags "$OPENMPFLAGS"
         lflags "$OPENMPFLAGS"
         status "OpenMP" "yes"
@@ -212,22 +207,22 @@
 fi
 
 # Cocoa
-if [[ "$OSTYPE" =~ "darwin" ]]; then
+if echo "$OSTYPE" | grep -q "darwin" ; then
     if [ -z "${MACOSX_DEPLOYMENT_TARGET+isset}" ]; then
         cflags "-mmacosx-version-min=10.9"
         lflags "-mmacosx-version-min=10.9"
     fi
 fi
 
-if [[ "$OSTYPE" =~ "darwin" ]]; then
+if echo "$OSTYPE" | grep -q "darwin" ; then
     SOLIBSUFFIX=dylib
 
     # Search Developer SDK paths, since Apple seems to have dropped the standard Unixy ones
     XCODE_CMD="xcode-select"
     XCODE_PATH=$($XCODE_CMD -p)
-    DIRS+=("$XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib")
-    DIRS+=("$XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/lib")
-elif [[ "$OSTYPE" =~ "msys" ]]; then
+    DIRS="$DIRS $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib"
+    DIRS="$DIRS $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include $XCODE_PATH/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/lib"
+elif echo "$OSTYPE" | grep -q "msys" ; then
     SOLIBSUFFIX=dll
 else
     SOLIBSUFFIX=so