Work on if, call and system tags.

__system.cpp

@@ -0,0 +1,57 @@
+#include "__call.h"
+#include "Exception.h"
+#include "MString.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+namespace jet {
+   
+   __call::__call(coreutils::ZString &in, coreutils::MString &out, Global &global) : Tag(in, out, global) {
+      if(hasContainer)
+	throw coreutils::Exception("call cannot have a container.");	
+      if(!variableDefined(coreutils::ZString("pgm")))
+	throw coreutils::Exception("pgm keyword must be specified.");
+      argv[0] = variables["pgm"].c_str(); // TODO: Need to peel off the program name only and pass as argv[0].	   
+      for(ix = 1; ix <= 50; ++ix) {    
+	 coreutils::MString arg("arg");
+	 arg << ix;
+	 if(variableDefined(arg))
+	   argv[ix] = variables[arg].c_str();
+	 else
+	   break;
+      }
+      argv[ix] == NULL;      
+      pipe(fdo);
+      pid = fork();
+      if(pid == 0) {
+	 close(fdo[0]);
+	 dup2(fdo[1], 1);
+	 if(variableDefined("input")) {
+	    coreutils::ZString input(variables[variables["input"]]);
+	    pipe(fdi);
+	    if(fork() == 0) {
+	       close(fdi[0]);
+	       write(fdi[1], input.getData(), input.getLength());
+	       close(fdi[1]);
+	       exit(0);
+	    }
+	    close(fdi[0]);
+	    dup2(fdi[0], 0);
+	 }
+	 rc = execve(variables["pgm"].c_str(), argv, NULL);
+	 close(fdo[1]);
+	 std::cout << "rc: " << rc << std::endl;
+	 exit(rc);
+      }
+      close(fdo[1]);
+      if(variableDefined("name")) 
+	global.variables[variables["name"]].read(fdo[0]); 	 
+      else 
+	out.read(fdo[0]);               
+      waitpid(pid, &status, 0);
+      std::cout << "status: " << status << std::endl;
+   }
+   
+}