add d scripts to read uptime and logged in user

chp05/proc/d/build

@@ -0,0 +1,4 @@
+#!/bin/bash
+echo "Building the D example scripts readuptime and whologgedin"
+gdc readUptime.d -o readUptime
+gdc whologgedin.d -o whologgedin

chp05/proc/d/readUptime.d

@@ -0,0 +1,23 @@
+import std.file;
+import std.stdio;
+import std.conv;
+import std.string;
+
+int main(string[] args)
+{
+   enum int SECONDS_PER_MINUTE = 60;
+   enum int PERCENT_BASE = 100;
+   writeln("Starting the read uptime program");
+   enum string PROC_UPTIME_PATH = "/proc/uptime";
+   auto procUptime = File(PROC_UPTIME_PATH, "r");
+   string upAndIdleTime = chop(procUptime.readln());
+   auto upAndIdleTimeInArray = upAndIdleTime.split(" ");
+   string uptimeString = upAndIdleTimeInArray[0];
+   string idletimeString = upAndIdleTimeInArray[1];
+   float uptime = to!float(uptimeString);
+   float idletime = to!float(idletimeString);
+   writefln("The system up time is %f minutes.", uptime/SECONDS_PER_MINUTE, " minutes.");
+   writefln("It was idle for %f minutes, or %f percent.", idletime/SECONDS_PER_MINUTE, PERCENT_BASE*(idletime/uptime));
+   procUptime.close();
+   return 0;
+}

chp05/proc/d/whologgedin.d

@@ -0,0 +1,8 @@
+import std.stdio;
+import core.sys.posix.unistd;
+
+int main(string[] args)
+{
+    writefln("The user logged in is %s.", getlogin());
+    return 0;
+}