add sleep() and sleep command

clite/commands.js

@@ -1535,6 +1535,53 @@ Options:
 	return main(args);
 });
 
+clite.commands.load('sleep',function(args,env,io) {
+	var stdio = io.include('stdio');
+	var stdlib = io.include('stdlib');
+
+	function help() {
+		stdio.printf(`
+sleep - suspend execution for a time
+Usage: sleep [OPTION] <SECONDS>
+
+Options:
+-?	Print this help information
+`);
+	}
+
+	function scb(r) {
+		io.exit(0);
+	}
+
+	function main(args) {
+		var seconds = 0;
+		for (var i=1; i<args.length; i++) {
+			if (args[i][0] == '-') {
+				for (var j=1; j<args[i].length; j++) {
+					switch (args[i][j]) {
+					case '?':
+						help();
+						return 0;
+						break;
+					default:
+						stdio.fprintf(io.stderr,'unknown argument: -%c\n',args[i][j]);
+					}
+				}
+			}else{
+				seconds = parseInt(args[i]);
+			}
+		}
+		if (seconds < 1)
+			return 0;
+
+		if (!stdlib.sleep(seconds,scb))
+			return 1;
+		return null;
+	}
+
+	return main(args);
+});
+
 if (window.location.protocol == 'file:')
 clite.commands.load('test',function(args,env,io) {
 	var stdio = io.include('stdio');

clite/core.js

@@ -32,9 +32,11 @@ var clite = {
 			}
 			return true;
 		},
-		execSafeAsync:function(f) {
+		execSafeAsync:function(f,delay) {
+			if (typeof delay !== 'number')
+				delay = 10;
 			try{
-				setTimeout(f,10);
+				setTimeout(f,delay);
 			} catch(e) {
 				clite.log.write(e.message);
 				return false;

clite/libstd.js

@@ -92,6 +92,12 @@ return Object.create({
 	// wait for all child processes to exit
 	waitall:function(cb) {
 		return clite.proc.addWaitGroupAll(io.pid,cb);
+	},
+
+	sleep:function(seconds,cb) {
+		return clite.core.execSafeAsync(function() {
+			cb(0);
+		},seconds*1000);
 	}
 
 });