melting-pot: explicitly check for prerequisites

That way, things won't explode in weird ways.

Author: ctrueden

melting-pot.sh

@@ -68,7 +68,6 @@
 # assumption will not be properly overridden in the melting pot!
 #
 # Author: Curtis Rueden
-# Dependencies: git, mvn, xmllint
 # ============================================================================
 
 # -- Functions --
@@ -96,6 +95,19 @@ unknownArg(){
  usage=1
 }
 
+checkPrereqs(){
+while [ $#-gt 0 ]
+do
+ which $1> /dev/null 2> /dev/null
+test$? -ne 0 &&echo"Missing prerequisite: $1"&&exit 255
+shift
+done
+}
+
+verifyPrereqs(){
+ checkPrereqs git mvn xmllint
+}
+
 parseArguments(){
 while [ $#-gt 0 ]
 do
@@ -531,6 +543,7 @@ meltDown(){
 
 # -- Main --
 
+verifyPrereqs
 parseArguments $@
 createDir "$outputDir"
 meltDown "$project"