diff --git a/scripts/test.sh b/scripts/test.sh
index e21918e..08e3deb 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -2,14 +2,12 @@
 
 JS_SLANG="node --stack-size=4000 node_modules/js-slang/dist/repl/repl.js"
 
-# must use BSD awk
-AWK="awk"
-
 SOURCEFILES=src/*/*.js
 SOURCE_TEST="src/test/framework/main.js"
 
 DEFAULT_CHAPTER=4
-DEFAULT_VARIANT="default"
+DEFAULT_VARIANT='default'
+DEFAULT_EXECUTION_METHOD=''
 
 red=`tput setaf 1`
 green=`tput setaf 2`
@@ -22,6 +20,7 @@ failed=0
 # $2 is the test file
 # $3 is the chapter
 # $4 is the variant
+# $5 specifies the execution method. '-i' for 'interpreter'. '' for 'native'.
 
 test_source() {
     # read in test file to find the number of comment lines
@@ -42,7 +41,7 @@ test_source() {
 
     # if program throws error, ignore the output and compare the error message only
     # NOTE: error output line is striped of line number as it is machine dependent
-    ERROR=$( { $JS_SLANG -e --chapter=$3 "$(cat $1 $2)">$DIR/__tests__/output; } 2>&1 )
+    ERROR=$( { $JS_SLANG $5 -e --chapter=$3 --variant=$4 "$(cat $1 $2)">$DIR/__tests__/output; } 2>&1 )
     if [ ! -z "$ERROR" ]
     then
         DIFF=$(diff <(echo $ERROR | grep -o 'Error:.*') <(cat $2 | tail -$NUM_VALID_COMMENT | grep -o 'Error:.*'))
@@ -61,24 +60,23 @@ $DIFF"
 }
 
 test_source_framework() {
-
     # run concatenation of source-test framework, source and test files
-    RESULTS=$($JS_SLANG -e --chapter=$3 --variant=$4 "$(cat $SOURCE_TEST $1 $2)")
+    RESULTS=$($JS_SLANG $5 -e --chapter=$3 --variant=$4 "$(cat $SOURCE_TEST $1 $2)")
     
     # retrieve names for tests that passed
     while read test_name
     do 
         passed=$(($passed+1))
         echo "${green}PASS $2 $test_name"
-    done < <(echo ${RESULTS} | grep -o '\w* PASSED' | $AWK -F 'PASSED' '{ print $1 }')
+    done < <(echo ${RESULTS} | grep -o '\w* PASSED' | cut -d ' ' -f 1)
     
     # retrieve names and error messages for tests that failed
     while read test_info 
     do 
         failed=$(($failed+1))
-        echo $test_info | $AWK -F 'FAILED:' '{ print $1 ":" $2 }' | $AWK -F '"' '{ print $1 $2 }' | 
+        echo $test_info | grep -o 'FAILED:.*' | cut -d ' ' -f 2- | 
             while read test_name test_error 
-            do echo "${red}FAIL $2 $test_name $test_error"; 
+            do echo "${red}FAIL $2 $test_name : $test_error"; 
             done
     done < <(echo ${RESULTS} | grep -o '\w* FAILED:[^"]*')
 }
@@ -94,17 +92,29 @@ main() {
 	    for i in "$DIR/__tests__/$(basename ${s} .js)".*
 	    do
         if [ -f "$i" ]; then
-            # check if first line of test file contains 'chapter=' and retrieve its value. Set to the default chapter if it does not
-            chapter=$($AWK -F 'chapter=' 'FNR==1{ if ($0~"chapter=") { print $2 } else { print '$DEFAULT_CHAPTER' } }' $i | $AWK -F ' ' '{ print $1 }')
-        
-            # check if first line of test file contains 'variant=' and retrieve its value. Set to the default variant if it does not
-            variant=$($AWK -F 'variant=' 'FNR==1{ if ($0~"variant=") { print $2 } else { print '$DEFAULT_VARIANT' } }' $i | $AWK -F ' ' '{ print $1 }')
+            ### check if first line of test file contains various keys and retrieve their values ###
+
+            chapter=$(cat $i | head -n1 | grep -o 'chapter=.*' | cut -d '=' -f 2 | cut -d ' ' -f 1)
+            if [ "$chapter" = "" ]
+            then chapter=$DEFAULT_CHAPTER
+            fi
+
+            variant=$(cat $i | head -n1 | grep -o 'variant=.*' | cut -d '=' -f 2 | cut -d ' ' -f 1)
+            if [ "$variant" = "" ]
+            then variant=$DEFAULT_VARIANT
+            fi
+
+            execution_method=$(cat $i | head -n1 | grep -o 'executionMethod=.*' | cut -d '=' -f 2 | cut -d ' ' -f 1)
+            if [ "$execution_method" = "interpreter" ]
+            then execution_method='-i'
+            else execution_method=$DEFAULT_EXECUTION_METHOD
+            fi
             
             # check if first line of test file contains 'framework'
-            use_source_test=$($AWK 'FNR==1{ if ($0~"framework") print "yes" }' $i)
-            if [[ $use_source_test == "yes" ]]
-            then chapter=4 ; test_source_framework $s $i $chapter $variant
-            else test_source $s $i $chapter $variant
+            use_source_test=$(cat $i | head -n1 | grep -o 'framework')
+            if [[ $use_source_test == "framework" ]]
+            then chapter=4 ; test_source_framework $s $i $chapter $variant $execution_method
+            else test_source $s $i $chapter $variant $execution_method
             fi
         fi
         done