diff --git a/clite/commands.js b/clite/commands.js
index c5411ae..194ed29 100644
--- a/clite/commands.js
+++ b/clite/commands.js
@@ -1744,10 +1744,17 @@ Options:
 		// -primary_operator primary_operand
 		if (uargs.length == 2) {
 			switch (uargs[0]) {
-			case '-b':	// test for a block file (don't exist, always false)
+			case '-b':	// test for a block file
+				var p = clite.resolvePath(uargs[1]);
+				var st = stdio.stat(p);
+				if (!st || (st.st_mode&stdio.modes.S_IFBLK) != stdio.modes.S_IFBLK) {
+					if (negate)
+						return 0;
+					return 1;
+				}
 				if (negate)
-					return 0;
-				return 1;
+					return 1;
+				return 0;
 				break;
 			case '-c':
 				var p = clite.resolvePath(uargs[1]);
@@ -1797,10 +1804,17 @@ Options:
 					return 1;
 				return 0;
 				break;
-			case '-g':	// test for set-groud-id (doesn't exist, always false)
+			case '-g':	// test for set-groud-id
+				var p = clite.resolvePath(uargs[1]);
+				var st = stdio.stat(p);
+				if (!st || (st.st_mode&stdio.modes.S_ISGID) != stdio.modes.S_ISGID) {
+					if (negate)
+						return 0;
+					return 1;
+				}
 				if (negate)
-					return 0;
-				return 1;
+					return 1;
+				return 0;
 				break;
 			case '-h':
 			case '-L':
@@ -1825,10 +1839,17 @@ Options:
 					return 1;
 				return 0;
 				break;
-			case '-p':	// test for FIFO/pipe (doesn't exist, always false)
+			case '-p':	// test for FIFO/pipe
+				var p = clite.resolvePath(uargs[1]);
+				var st = stdio.stat(p);
+				if (!st || (st.st_mode&stdio.modes.S_IFIFO) != stdio.modes.S_IFIFO) {
+					if (negate)
+						return 0;
+					return 1;
+				}
 				if (negate)
-					return 0;
-				return 1;
+					return 1;
+				return 0;
 				break;
 			case '-r':
 				var p = clite.resolvePath(uargs[1]);
@@ -1846,10 +1867,17 @@ Options:
 					return 1;
 				return 0;
 				break;
-			case '-S':	// test for socket (doesn't exist, always false)
+			case '-S':	// test for socket
+				var p = clite.resolvePath(uargs[1]);
+				var st = stdio.stat(p);
+				if (!st || (st.st_mode&stdio.modes.S_IFSOCK) != stdio.modes.S_IFSOCK) {
+					if (negate)
+						return 0;
+					return 1;
+				}
 				if (negate)
-					return 0;
-				return 1;
+					return 1;
+				return 0;
 				break;
 			case '-s':
 				var p = clite.resolvePath(uargs[1]);
@@ -1898,10 +1926,17 @@ Options:
 					return 0;
 				return 1;
 				break;
-			case '-u':	// test for set-user-id (doesn't exist, always false)
+			case '-u':	// test for set-user-id
+				var p = clite.resolvePath(uargs[1]);
+				var st = stdio.stat(p);
+				if (!st || (st.st_mode&stdio.modes.S_ISUID) != stdio.modes.S_ISUID) {
+					if (negate)
+						return 0;
+					return 1;
+				}
 				if (negate)
-					return 0;
-				return 1;
+					return 1;
+				return 0;
 				break;
 			case '-w':
 				var p = clite.resolvePath(uargs[1]);
diff --git a/clite/core.js b/clite/core.js
index c3e98c5..d0dccc3 100644
--- a/clite/core.js
+++ b/clite/core.js
@@ -744,6 +744,28 @@ clite.proc = {
 				return 0;
 			return proc.gid;
 		}
+		clite.proc.setUID = function(pid,uid,force) {
+			var proc = getProc(pid);
+			if (!proc)
+				return false;
+			if (!clite.user.getPWData(uid))
+				return false;
+			if (!force && proc.uid != 0)
+				return false;
+			proc.uid = uid;
+			return true;
+		}
+		clite.proc.setGID = function(pid,gid,force) {
+			var proc = getProc(pid);
+			if (!proc)
+				return false;
+			if (!clite.user.getGRData(gid))
+				return false;
+			if (!force && gid == 0)
+				return false;
+			proc.gid = gid;
+			return true;
+		}
 		clite.proc.getTTY = function(pid) {
 			var proc = getProc(pid);
 			if (!proc)
@@ -1394,7 +1416,7 @@ clite.io = {
 			if (typeof mode != 'number')
 				return false;
 			var uid = clite.proc.getUID(pid);
-			if (fd.node.uid != uid)
+			if (fd.node.uid != uid && uid != 0)
 				return false;
 
 			mode &= ~clite.io.modes.S_IFMT;
@@ -2942,6 +2964,16 @@ clite.lib = {
 			return -4;
 		}
 
+		if ((fd.node.mode&clite.io.modes.S_ISGID) == clite.io.modes.S_ISGID) {
+			if (!clite.proc.setGID(io.pid,fd.node.gid,true))
+				return -7;
+		}
+
+		if ((fd.node.mode&clite.io.modes.S_ISUID) == clite.io.modes.S_ISUID) {
+			if (!clite.proc.setUID(io.pid,fd.node.uid,true))
+				return -8;
+		}
+
 		clite.proc.update(args.join(' '));
 
 		var r = clite.core.execSafe(function() {
diff --git a/clite/libstd.js b/clite/libstd.js
index edf6f24..a7f1293 100644
--- a/clite/libstd.js
+++ b/clite/libstd.js
@@ -47,6 +47,9 @@ return Object.create({
 	getuid:function() {
 		return clite.proc.getUID(io.pid);
 	},
+	setuid:function(id) {
+		return clite.proc.setUID(io.pid,id,false);
+	},
 
 	// gets the passwd file data for a user based on their uid
 	getpwuid:function(uid) {
@@ -64,6 +67,9 @@ return Object.create({
 	getgid:function() {
 		return clite.proc.getGID(io.pid);
 	},
+	setgid:function(id) {
+		return clite.proc.setGID(io.pid,id,false);
+	},
 
 	// gets teh group file data for a group based on their gid
 	getgrgid:function(gid) {
diff --git a/clite/shell.js b/clite/shell.js
index 61b36ca..21ee312 100644
--- a/clite/shell.js
+++ b/clite/shell.js
@@ -421,6 +421,12 @@ clite.commands.load('sh',function(args,env,io) {
 					return;
 				}
 
+				if (r == -7 || r == -8) {
+					stdio.fprintf(io.stderr,'Shell: failed to set uid/gid for: %s\n',exec.active.args[0]);
+					io.exit(-3);
+					return;
+				}
+
 				if (r<0) {
 					stdio.fprintf(io.stderr,'Shell: could not exec file: %s\n',exec.active.args[0]);
 					io.exit(-3);