diff --git a/base64/base64.rs b/base64/base64.rs
index fd240f5b4..b42010304 100644
--- a/base64/base64.rs
+++ b/base64/base64.rs
@@ -35,7 +35,7 @@ mod util;
 
 static NAME: &'static str = "base64";
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         optflag("d", "decode", "decode data"),
         optflag("i", "ignore-garbage", "when decoding, ignore non-alphabetic characters"),
@@ -88,10 +88,12 @@ pub fn uumain(args: Vec<String>) {
         Help    => help(progname.as_slice(), usage.as_slice()),
         Version => version()
     }
+
+    return 0;
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
 fn decode(input: &mut Reader, ignore_garbage: bool) {
     let mut to_decode = match input.read_to_str() {
diff --git a/basename/basename.rs b/basename/basename.rs
index e3c170ba1..8f5b2f3ee 100644
--- a/basename/basename.rs
+++ b/basename/basename.rs
@@ -24,9 +24,9 @@ static NAME: &'static str = "basename";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = strip_dir(args.get(0).as_slice());
 
     //
@@ -50,25 +50,25 @@ pub fn uumain(args: Vec<String>) {
 
         print(getopts::usage("", opts).as_slice());
 
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("{} {}", program, VERSION);
-        return;
+        return 0;
     }
 
     // too few arguments
     if args.len() < 2 {
         println!("{}: {}", program, "missing operand");
         println!("Try '{} --help' for more information.", program);
-        return;
+        return 0;
     }
     // too many arguments
     else if args.len() > 3 {
         println!("{}: extra operand '{}'", program, args.get(3));
         println!("Try '{} --help' for more information.", program);
-        return;
+        return 0;
     }
 
     //
@@ -85,6 +85,8 @@ pub fn uumain(args: Vec<String>) {
     }
 
     println(name.as_slice());
+
+    return 0;
 }
 
 fn strip_dir(fullname: &str) -> String {
diff --git a/cat/cat.rs b/cat/cat.rs
index 557a9feef..ba8fad3f5 100644
--- a/cat/cat.rs
+++ b/cat/cat.rs
@@ -20,9 +20,9 @@ use std::io::{IoResult};
 use std::ptr::{copy_nonoverlapping_memory};
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         getopts::optflag("A", "show-all", "equivalent to -vET"),
@@ -53,11 +53,11 @@ pub fn uumain(args: Vec<String>) {
                              standard output.", opts).as_slice());
         println!("");
         println!("With no FILE, or when FILE is -, read standard input.");
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("cat 1.0.0");
-        return;
+        return 0;
     }
 
     let mut number_mode = NumberNone;
@@ -80,6 +80,8 @@ pub fn uumain(args: Vec<String>) {
     }
 
     exec(files, number_mode, show_nonprint, show_ends, show_tabs, squeeze_blank);
+
+    return 0;
 }
 
 #[deriving(Eq, PartialEq)]
diff --git a/cksum/cksum.rs b/cksum/cksum.rs
index 6907a2e40..af6799437 100644
--- a/cksum/cksum.rs
+++ b/cksum/cksum.rs
@@ -78,9 +78,9 @@ fn open_file(name: &str) -> IoResult<Box<Reader>> {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); } 
+fn main() { os::set_exit_status(uumain(os::args())); } 
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
         getopts::optflag("V", "version", "output version information and exit"),
@@ -98,12 +98,12 @@ pub fn uumain(args: Vec<String>) {
         println!("  {} [OPTIONS] [FILE]...", NAME);
         println!("");
         print(getopts::usage("Print CRC and size for each file.", opts.as_slice()).as_slice());
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("{} {}", NAME, VERSION);
-        return;
+        return 0;
     }
 
     let files = matches.free;
@@ -113,7 +113,7 @@ pub fn uumain(args: Vec<String>) {
             Ok((crc, size)) => println!("{} {}", crc, size),
             Err(err) => show_error!(2, "{}", err),
         }
-        return
+        return 0;
     }
 
     for fname in files.iter() {
@@ -122,4 +122,6 @@ pub fn uumain(args: Vec<String>) {
             Err(err) => show_error!(2, "'{}' {}", fname, err),
         }
     }
+
+    return 0;
 }
diff --git a/comm/comm.rs b/comm/comm.rs
index 1cc1d2eeb..e2d669777 100644
--- a/comm/comm.rs
+++ b/comm/comm.rs
@@ -95,9 +95,9 @@ fn open_file(name: &str) -> IoResult<Box<Buffer>> {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         getopts::optflag("1", "", "suppress column 1 (lines uniq to FILE1)"),
         getopts::optflag("2", "", "suppress column 2 (lines uniq to FILE2)"),
@@ -114,7 +114,7 @@ pub fn uumain(args: Vec<String>) {
 
     if matches.opt_present("version") {
         println!("{} {}", NAME, VERSION);
-        return;
+        return 0;
     }
 
     if matches.opt_present("help") || matches.free.len() != 2 {
@@ -125,14 +125,16 @@ pub fn uumain(args: Vec<String>) {
         println!("");
         print(getopts::usage("Compare sorted files line by line.", opts.as_slice()).as_slice());
         if matches.free.len() != 2 {
-            os::set_exit_status(1);
+            return 0;
         }
-        return;
+        return 0;
     }
 
 
     let mut f1 = open_file(matches.free.get(0).as_slice()).unwrap();
     let mut f2 = open_file(matches.free.get(1).as_slice()).unwrap();
 
-    comm(&mut f1, &mut f2, &matches)
+    comm(&mut f1, &mut f2, &matches);
+
+    return 0;
 }
diff --git a/cp/cp.rs b/cp/cp.rs
index 7176d9007..b23eb2c6a 100644
--- a/cp/cp.rs
+++ b/cp/cp.rs
@@ -32,9 +32,9 @@ pub enum Mode {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         optflag("h", "help", "display this help and exit"),
         optflag("", "version", "output version information and exit"),
@@ -62,6 +62,8 @@ pub fn uumain(args: Vec<String>) {
         Help    => help(progname.as_slice(), usage.as_slice()),
         Version => version(),
     }
+
+    return 0;
 }
 
 fn version() {
diff --git a/dirname/dirname.rs b/dirname/dirname.rs
index 196d7bef4..65a830793 100644
--- a/dirname/dirname.rs
+++ b/dirname/dirname.rs
@@ -17,9 +17,9 @@ use std::io::print;
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("z", "zero", "separate output with NUL rather than newline"),
@@ -41,11 +41,12 @@ pub fn uumain(args: Vec<String>) {
         print(getopts::usage("Output each NAME with its last non-slash component and trailing slashes
 removed; if NAME contains no  /'s,  output  '.'  (meaning  the  current
 directory).", opts).as_slice());
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
-        return println!("dirname version: {:s}", VERSION);
+        println!("dirname version: {:s}", VERSION);
+        return 0;
     }
 
     let separator = match matches.opt_present("zero") {
@@ -66,4 +67,6 @@ directory).", opts).as_slice());
         println!("{0:s}: missing operand", program);
         println!("Try '{0:s} --help' for more information.", program);
     }
+
+    return 0;
 }
diff --git a/du/du.rs b/du/du.rs
index 6bd1ad54d..0b57be8f0 100644
--- a/du/du.rs
+++ b/du/du.rs
@@ -90,9 +90,9 @@ fn du(path: &Path, mut my_stat: Stat,
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         // In task
@@ -163,7 +163,7 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(f) => {
             show_error!(1, "Invalid options\n{}", f.to_err_msg());
-            return
+            return 0;
         }
     };
 
@@ -187,10 +187,10 @@ ers of 1000).",
                  program = program,
                  version = VERSION,
                  usage = getopts::usage("Summarize disk usage of each FILE, recursively for directories.", opts));
-        return
+        return 0;
     } else if matches.opt_present("version") {
         println!("{} version: {}", program, VERSION);
-        return
+        return 0;
     }
 
     let summarize = matches.opt_present("summarize");
@@ -200,11 +200,11 @@ ers of 1000).",
     match (max_depth_str, max_depth) {
         (Some(ref s), _) if summarize => {
             println!("{}: warning: summarizing conflicts with --max-depth={:s}", program, *s);
-            return
+            return 0;
         }
         (Some(ref s), None) => {
             println!("{}: invalid maximum depth '{:s}'", program, *s);
-            return
+            return 0;
         }
         (Some(_), Some(_)) | (None, _) => { /* valid */ }
     }
@@ -239,7 +239,7 @@ ers of 1000).",
             for c in s.as_slice().chars() {
                 if found_letter && c.is_digit() || !found_number && !c.is_digit() {
                     println!("{}: invalid --block-size argument '{}'", program, s);
-                    return
+                    return 0;
                 } else if c.is_digit() {
                     found_number = true;
                     numbers.push(c as u8);
@@ -261,7 +261,7 @@ ers of 1000).",
                 "ZB" => 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000,
                 "YB" => 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000,
                 _ => {
-                    println!("{}: invalid --block-size argument '{}'", program, s); return
+                    println!("{}: invalid --block-size argument '{}'", program, s); return 0;
                 }
             };
             number * multiple
@@ -300,7 +300,7 @@ Valid arguments are:
 - 'long-iso'
 - 'iso'
 Try '{program} --help' for more information.", s, program = program);
-                    return
+                    return 0;
                 }
             }
         },
@@ -339,7 +339,7 @@ Try '{program} --help' for more information.", s, program = program);
     Valid arguments are:
       - 'accessed', 'created', 'modified'
     Try '{program} --help' for more information.", program = program);
-                                    return
+                                    return 0;
                                 }
                             },
                             None => stat.fstat.modified
@@ -366,4 +366,6 @@ Try '{program} --help' for more information.", s, program = program);
         print!("{:<10} total", convert_size(grand_total));
         print!("{}", line_separator);
     }
+
+    return 0;
 }
diff --git a/echo/echo.rs b/echo/echo.rs
index 75e798593..4d57d19a7 100644
--- a/echo/echo.rs
+++ b/echo/echo.rs
@@ -70,9 +70,9 @@ fn convert_str(string: &str, index: uint, base: uint) -> (char, int) {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("n", "", "do not output the trailing newline"),
@@ -109,11 +109,12 @@ pub fn uumain(args: Vec<String>) {
 \\v      vertical tab
 \\0NNN   byte with octal value NNN (1 to 3 digits)
 \\xHH    byte with hexadecimal value HH (1 to 2 digits)");
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
-        return println!("echo version: {:s}", VERSION);
+        println!("echo version: {:s}", VERSION);
+        return 0;
     }
 
     if !matches.free.is_empty() {
@@ -185,4 +186,6 @@ pub fn uumain(args: Vec<String>) {
     if !matches.opt_present("n") {
         println!("")
     }
+
+    return 0;
 }
diff --git a/env/env.rs b/env/env.rs
index b3d365af5..c02b962f3 100644
--- a/env/env.rs
+++ b/env/env.rs
@@ -54,9 +54,9 @@ fn print_env(null: bool) {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let prog = args.get(0).as_slice();
 
     // to handle arguments the same way than GNU env, we can't use getopts
@@ -97,8 +97,8 @@ pub fn uumain(args: Vec<String>) {
             }
         } else if opt.as_slice().starts_with("--") {
             match opt.as_slice() {
-                "--help" => { usage(prog); return }
-                "--version" => { version(); return }
+                "--help" => { usage(prog); return 0; }
+                "--version" => { version(); return 0; }
 
                 "--ignore-environment" => opts.ignore_env = true,
                 "--null" => opts.null = true,
@@ -114,7 +114,7 @@ pub fn uumain(args: Vec<String>) {
                 _ => {
                     println!("{:s}: invalid option \"{:s}\"", prog, *opt);
                     println!("Type \"{:s} --help\" for detailed informations", prog);
-                    return
+                    return 0;
                 }
             }
         } else if opt.as_slice().starts_with("-") {
@@ -131,8 +131,8 @@ pub fn uumain(args: Vec<String>) {
             for c in chars {
                 // short versions of options
                 match c {
-                    'h' => { usage(prog); return }
-                    'V' => { version(); return }
+                    'h' => { usage(prog); return 0; }
+                    'V' => { version(); return 0; }
                     'i' => opts.ignore_env = true,
                     '0' => opts.null = true,
                     'u' => {
@@ -146,7 +146,7 @@ pub fn uumain(args: Vec<String>) {
                     _ => {
                         println!("{:s}: illegal option -- {:c}", prog, c);
                         println!("Type \"{:s} --help\" for detailed informations", prog);
-                        return
+                        return 0;
                     }
                 }
             }
@@ -200,14 +200,16 @@ pub fn uumain(args: Vec<String>) {
         let args = opts.program.slice_from(1);
         match Command::new(prog).args(args).stdin(InheritFd(0)).stdout(InheritFd(1)).stderr(InheritFd(2)).status() {
             Ok(exit) =>
-                std::os::set_exit_status(match exit {
+                return match exit {
                     std::io::process::ExitStatus(s) => s,
                     _ => 1
-                }),
-            Err(_) => std::os::set_exit_status(1)
+                },
+            Err(_) => return 1
         }
     } else {
         // no program provided
         print_env(opts.null);
     }
+
+    return 0;
 }
diff --git a/fold/fold.rs b/fold/fold.rs
index e5ccc732b..5818e0fb8 100644
--- a/fold/fold.rs
+++ b/fold/fold.rs
@@ -27,9 +27,9 @@ static NAME: &'static str = "fold";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
 
     let (args, obs_width) = handle_obsolete(args.as_slice());
     let program = args.get(0).clone();
@@ -82,6 +82,8 @@ pub fn uumain(args: Vec<String>) {
         };
         fold(files, bytes, spaces, width);
     }
+
+    return 0;
 }
 
 fn handle_obsolete(args: &[String]) -> (Vec<String>, Option<String>) {
diff --git a/groups/groups.rs b/groups/groups.rs
index d344e9583..54abdbc92 100644
--- a/groups/groups.rs
+++ b/groups/groups.rs
@@ -26,9 +26,9 @@ use c_types::{get_pw_from_args, group};
 static NAME: &'static str = "groups";
 
 #[allow(dead_code)]
-fn main () { uumain(os::args()); }
+fn main () { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let options = [
             optflag("h", "", "Help")
         ];
@@ -37,9 +37,11 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => { m },
         Err(_) => {
             show_error!(1, "{}", usage(NAME, options));
-            return;
+            return 0;
         }
     };
 
     group(get_pw_from_args(&matches.free), true);
+
+    return 0;
 }
diff --git a/head/head.rs b/head/head.rs
index 70fe114df..6840588a4 100644
--- a/head/head.rs
+++ b/head/head.rs
@@ -23,9 +23,9 @@ use getopts::{optopt, optflag, getopts, usage};
 static PROGRAM: &'static str = "head";
 
 #[allow(dead_code)]
-fn main () { uumain(os::args()); }
+fn main () { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let mut line_count = 10u;
 
     // handle obsolete -number syntax
@@ -46,15 +46,15 @@ pub fn uumain(args: Vec<String>) {
         Ok (m) => { m }
         Err(_) => {
             println!("{:s}", usage(PROGRAM, possible_options));
-            return
+            return 0;
         }
     };
 
     if given_options.opt_present("h") {
         println!("{:s}", usage(PROGRAM, possible_options));
-        return;
+        return 0;
     }
-    if given_options.opt_present("V") { version(); return }
+    if given_options.opt_present("V") { version(); return 0 }
 
     match given_options.opt_str("n") {
         Some(n) => {
@@ -93,6 +93,8 @@ pub fn uumain(args: Vec<String>) {
             head(&mut buffer, line_count);
         }
     }
+
+    return 0;
 }
 
 // It searches for an option in the form of -123123
diff --git a/hostid/hostid.rs b/hostid/hostid.rs
index 6ce2d77e0..38aaefd24 100644
--- a/hostid/hostid.rs
+++ b/hostid/hostid.rs
@@ -50,9 +50,9 @@ extern {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
 
     let opts = [
         optflag("", "help", "display this help and exit"),
@@ -66,7 +66,7 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(e) => {
             show_error!(EXIT_ERR, "{}\n{}", e.to_err_msg(),  get_help_text(NAME, usage.as_slice()));
-            return
+            return 0;
         },
     };
 
@@ -83,6 +83,8 @@ pub fn uumain(args: Vec<String>) {
         Help    => help(NAME, usage.as_slice()),
         Version => version(),
     }
+
+    return 0;
 }
 
 fn version() {
diff --git a/hostname/hostname.rs b/hostname/hostname.rs
index f78dd1173..c0b7a3210 100644
--- a/hostname/hostname.rs
+++ b/hostname/hostname.rs
@@ -24,9 +24,9 @@ extern {
 }
 
 #[allow(dead_code)]
-fn main () { uumain(os::args()); }
+fn main () { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0);
 
     let options = [
@@ -38,14 +38,14 @@ pub fn uumain(args: Vec<String>) {
 
     let matches = match getopts(args.tail(), options) {
         Ok(m) => { m }
-        _ => { help_menu(program.as_slice(), options); return; }
+        _ => { help_menu(program.as_slice(), options); return 0; }
     };
 
     if matches.opt_present("h") {
         help_menu(program.as_slice(), options);
-        return
+        return 0
     }
-    if matches.opt_present("V") { version(); return }
+    if matches.opt_present("V") { version(); return 0 }
 
     match matches.free.len() {
         0 => {
@@ -55,7 +55,7 @@ pub fn uumain(args: Vec<String>) {
                 let pos = hostname.as_slice().find_str(".");
                 if pos.is_some() {
                     println!("{:s}", hostname.as_slice().slice_to(pos.unwrap()));
-                    return;
+                    return 0;
                 }
             }
 
@@ -64,6 +64,8 @@ pub fn uumain(args: Vec<String>) {
         1 => { xsethostname( matches.free.last().unwrap().as_slice() ) }
         _ => { help_menu(program.as_slice(), options); }
     };
+
+    return 0;
 }
 
 fn version() {
diff --git a/id/id.rs b/id/id.rs
index cd3c4364d..b61ee9a9d 100644
--- a/id/id.rs
+++ b/id/id.rs
@@ -88,9 +88,9 @@ extern {
 static NAME: &'static str = "id";
 
 #[allow(dead_code)]
-fn main () { uumain(os::args()); }
+fn main () { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let args_t = args.tail();
 
     let options = [
@@ -109,18 +109,18 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => { m },
         Err(_) => {
             println!("{:s}", usage(NAME, options));
-            return;
+            return 0;
         }
     };
 
     if matches.opt_present("h") {
         println!("{:s}", usage(NAME, options));
-        return;
+        return 0;
     }
 
     if matches.opt_present("A") {
         auditid();
-        return;
+        return 0;
     }
 
 
@@ -149,7 +149,7 @@ pub fn uumain(args: Vec<String>) {
         } else {
             println!("{:u}", id);
         }
-        return;
+        return 0;
     }
 
     if uflag {
@@ -171,22 +171,22 @@ pub fn uumain(args: Vec<String>) {
             println!("{:d}", id);
         }
 
-        return;
+        return 0;
     }
 
     if matches.opt_present("G") {
         group(possible_pw, nflag);
-        return;
+        return 0;
     }
 
     if matches.opt_present("P") {
         pline(possible_pw);
-        return;
+        return 0;
     };
 
     if matches.opt_present("p") {
         pretty(possible_pw);
-        return;
+        return 0;
     }
 
     if possible_pw.is_some() {
@@ -194,6 +194,8 @@ pub fn uumain(args: Vec<String>) {
     } else {
         id_print(possible_pw, false, true, true)
     }
+
+    return 0;
 }
 
 fn pretty(possible_pw: Option<c_passwd>) {
diff --git a/kill/kill.rs b/kill/kill.rs
index f2dbe8b3e..0e48b6306 100644
--- a/kill/kill.rs
+++ b/kill/kill.rs
@@ -53,9 +53,9 @@ pub enum Mode {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
 
     let opts = [
         optflag("h", "help", "display this help and exit"),
@@ -72,7 +72,7 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(e) => {
             show_error!(EXIT_ERR, "{}\n{}", e.to_err_msg(),  get_help_text(NAME, usage.as_slice()));
-            return
+            return 0
         },
     };
 
@@ -96,6 +96,8 @@ pub fn uumain(args: Vec<String>) {
         Help    => help(NAME, usage.as_slice()),
         Version => version(),
     }
+
+    return 0;
 }
 
 fn version() {
diff --git a/logname/logname.rs b/logname/logname.rs
index 1e6ea6650..4f34eb40b 100644
--- a/logname/logname.rs
+++ b/logname/logname.rs
@@ -44,9 +44,9 @@ fn version() {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     //
@@ -69,14 +69,16 @@ pub fn uumain(args: Vec<String>) {
         println!("  {:s}", program);
         println!("");
         print(getopts::usage("print user's login name", opts).as_slice());
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         version();
-        return;
+        return 0;
     }
 
     exec();
+
+    return 0;
 }
 
 fn exec() {
diff --git a/md5sum/md5sum.rs b/md5sum/md5sum.rs
index b368e302a..25c0f0b78 100644
--- a/md5sum/md5sum.rs
+++ b/md5sum/md5sum.rs
@@ -27,8 +27,10 @@ mod util;
 static NAME: &'static str = "md5sum";
 static VERSION: &'static str = "1.0.0";
 
-fn main() {
-    let args = os::args();
+#[allow(dead_code)]
+fn main() { os::set_exit_status(uumain(os::args())); }
+
+pub fn uumain(args: Vec<String>) -> int {
 
     let program = args.get(0).clone();
 
@@ -72,11 +74,16 @@ fn main() {
         } else {
             matches.free
         };
-        md5sum(files, binary, check, tag, status, quiet, strict, warn);
+        match md5sum(files, binary, check, tag, status, quiet, strict, warn) {
+            Ok(()) => return 0,
+            Err(e) => return e
+        }
     }
+
+    return 0;
 }
 
-fn md5sum(files: Vec<String>, binary: bool, check: bool, tag: bool, status: bool, quiet: bool, strict: bool, warn: bool) {
+fn md5sum(files: Vec<String>, binary: bool, check: bool, tag: bool, status: bool, quiet: bool, strict: bool, warn: bool) -> Result<(), int> {
     let mut md5 = crypto::md5::Md5::new();
     let bytes = md5.output_bits() / 4;
     let mut bad_format = 0;
@@ -102,7 +109,7 @@ fn md5sum(files: Vec<String>, binary: bool, check: bool, tag: bool, status: bool
                         None => {
                             bad_format += 1;
                             if strict {
-                                os::set_exit_status(1);
+                                return Err(1);
                             }
                             if warn {
                                 show_warning!("{}: {}: improperly formatted MD5 checksum line", filename, i + 1);
@@ -121,7 +128,7 @@ fn md5sum(files: Vec<String>, binary: bool, check: bool, tag: bool, status: bool
                         println!("{}: FAILED", ck_filename);
                     }
                     failed += 1;
-                    os::set_exit_status(1);
+                    return Err(1);
                 }
             }
         } else {
@@ -143,6 +150,8 @@ fn md5sum(files: Vec<String>, binary: bool, check: bool, tag: bool, status: bool
             show_warning!("{} computed checksum did NOT match", failed);
         }
     }
+
+    return Ok(());
 }
 
 fn calc_sum(md5: &mut crypto::md5::Md5, file: &mut Reader, binary: bool) -> String {
diff --git a/mkdir/mkdir.rs b/mkdir/mkdir.rs
index eb88c1942..07a0fb6af 100644
--- a/mkdir/mkdir.rs
+++ b/mkdir/mkdir.rs
@@ -29,9 +29,9 @@ static VERSION: &'static str = "1.0.0";
  * Handles option parsing
  */
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
 
     let opts = [
         // Linux-specific options, not implemented
@@ -54,11 +54,11 @@ pub fn uumain(args: Vec<String>) {
 
     if args.len() == 1 || matches.opt_present("help") {
         print_help(opts);
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("mkdir v{}", VERSION);
-        return;
+        return 0;
     }
     let verbose_flag = matches.opt_present("verbose");
     let mk_parents = matches.opt_present("parents");
@@ -85,6 +85,8 @@ pub fn uumain(args: Vec<String>) {
         crash!(1, "missing operand");
     }
     exec(dirs, mk_parents, mode, verbose_flag);
+
+    return 0;
 }
 
 fn print_help(opts: &[getopts::OptGroup]) {
diff --git a/paste/paste.rs b/paste/paste.rs
index 31b55d681..9d55185fe 100644
--- a/paste/paste.rs
+++ b/paste/paste.rs
@@ -24,9 +24,9 @@ static NAME: &'static str = "paste";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     let opts = [
@@ -56,6 +56,8 @@ pub fn uumain(args: Vec<String>) {
         };
         paste(matches.free, serial, delimiters.as_slice());
     }
+
+    return 0;
 }
 
 fn paste(filenames: Vec<String>, serial: bool, delimiters: &str) {
diff --git a/printenv/printenv.rs b/printenv/printenv.rs
index 1df80e271..f0e928ca4 100644
--- a/printenv/printenv.rs
+++ b/printenv/printenv.rs
@@ -25,9 +25,9 @@ mod util;
 static NAME: &'static str = "printenv";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("0", "null", "end each output line with 0 byte rather than newline"),
@@ -47,11 +47,11 @@ pub fn uumain(args: Vec<String>) {
         println!("  {0:s} [VARIABLE]... [OPTION]...", program);
         println!("");
         print(getopts::usage("Prints the given environment VARIABLE(s), otherwise prints them all.", opts).as_slice());
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("printenv 1.0.0");
-        return;
+        return 0;
     }
     let mut separator = "\n";
     if matches.opt_present("null") {
@@ -59,6 +59,8 @@ pub fn uumain(args: Vec<String>) {
     };
 
     exec(matches.free, separator);
+
+    return 0;
 }
 
 pub fn exec(args: Vec<String>, separator: &str) {
diff --git a/pwd/pwd.rs b/pwd/pwd.rs
index e8831237c..a89b5b906 100644
--- a/pwd/pwd.rs
+++ b/pwd/pwd.rs
@@ -24,9 +24,9 @@ static NAME: &'static str = "pwd";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("", "help", "display this help and exit"),
@@ -48,9 +48,15 @@ pub fn uumain(args: Vec<String>) {
         println!("");
         print(getopts::usage("Print the full filename of the current working directory.", opts).as_slice());
     } else if matches.opt_present("version") {
-        return println!("pwd version: {}", VERSION);
+        println!("pwd version: {}", VERSION);
+
+        return 0;
     } else {
         let cwd = std::os::getcwd();
         println!("{}", cwd.display());
+
+        return 0;
     }
+
+    return 0;
 }
diff --git a/rm/rm.rs b/rm/rm.rs
index 057013c1b..44f46e5d6 100644
--- a/rm/rm.rs
+++ b/rm/rm.rs
@@ -30,9 +30,9 @@ enum InteractiveMode {
 static NAME: &'static str = "rm";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     // TODO: make getopts support -R in addition to -r
@@ -113,12 +113,14 @@ pub fn uumain(args: Vec<String>) {
                     "Remove all arguments? "
                 };
             if !prompt(msg) {
-                return;
+                return 0;
             }
         }
         remove(matches.free, force, interactive, one_fs, preserve_root,
                recursive, dir, verbose);
     }
+
+    return 0;
 }
 
 // TODO: implement one-file-system
diff --git a/rmdir/rmdir.rs b/rmdir/rmdir.rs
index 14052754c..cd9020900 100644
--- a/rmdir/rmdir.rs
+++ b/rmdir/rmdir.rs
@@ -23,9 +23,9 @@ mod util;
 static NAME: &'static str = "rmdir";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     let opts = [
@@ -39,7 +39,7 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(f) => {
             show_error!(1, "{}", f.to_err_msg());
-            return;
+            return 0;
         }
     };
 
@@ -61,6 +61,8 @@ pub fn uumain(args: Vec<String>) {
         let verbose = matches.opt_present("verbose");
         remove(matches.free, ignore, parents, verbose);
     }
+
+    return 0;
 }
 
 fn remove(dirs: Vec<String>, ignore: bool, parents: bool, verbose: bool) {
diff --git a/seq/seq.rs b/seq/seq.rs
index c0c098763..f0d068a87 100644
--- a/seq/seq.rs
+++ b/seq/seq.rs
@@ -34,9 +34,9 @@ fn escape_sequences(s: &str) -> String {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         getopts::optopt("s", "separator", "Separator character (defaults to \\n)", ""),
         getopts::optopt("t", "terminator", "Terminator character (defaults to separator)", ""),
@@ -49,26 +49,25 @@ pub fn uumain(args: Vec<String>) {
         Err(f) => {
             show_error!(1, "{:s}", f.to_err_msg());
             print_usage(opts);
-            return;
+            return 0;
         }
     };
     if matches.opt_present("help") {
         print_usage(opts);
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("seq 1.0.0");
-        return;
+        return 0;
     }
     if matches.free.len() < 1 || matches.free.len() > 3 {
-        os::set_exit_status(1);
         print_usage(opts);
-        return;
+        return 1;
     }
     let first = if matches.free.len() > 1 {
         match parse_float(matches.free.get(0).as_slice()) {
             Ok(n) => n,
-            Err(s) => { show_error!(1, "{:s}", s); return; }
+            Err(s) => { show_error!(1, "{:s}", s); return 0; }
         }
     } else {
         1.0
@@ -76,18 +75,20 @@ pub fn uumain(args: Vec<String>) {
     let step = if matches.free.len() > 2 {
         match parse_float(matches.free.get(1).as_slice()) {
             Ok(n) => n,
-            Err(s) => { show_error!(1, "{:s}", s); return; }
+            Err(s) => { show_error!(1, "{:s}", s); return 0; }
         }
     } else {
         1.0
     };
     let last = match parse_float(matches.free.get(matches.free.len()-1).as_slice()) {
         Ok(n) => n,
-        Err(s) => { show_error!(1, "{:s}", s); return; }
+        Err(s) => { show_error!(1, "{:s}", s); return 0; }
     };
     let separator = escape_sequences(matches.opt_str("s").unwrap_or("\n".to_string()).as_slice());
     let terminator = escape_sequences(matches.opt_str("t").unwrap_or(separator.to_string()).as_slice());
     print_seq(first, step, last, separator, terminator, matches.opt_present("w"));
+
+    return 0;
 }
 
 fn done_printing(next: f32, step: f32, last: f32) -> bool {
diff --git a/sleep/sleep.rs b/sleep/sleep.rs
index fe020fa8f..64c3f0828 100644
--- a/sleep/sleep.rs
+++ b/sleep/sleep.rs
@@ -24,9 +24,9 @@ mod util;
 static NAME: &'static str = "sleep";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     let opts = [
@@ -37,7 +37,7 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(f) => {
             show_error!(1, "{}", f.to_err_msg());
-            return
+            return 0;
         }
     };
 
@@ -62,6 +62,8 @@ specified by the sum of their values.", opts).as_slice());
     } else {
         sleep(matches.free);
     }
+
+    return 0;
 }
 
 fn sleep(args: Vec<String>) {
diff --git a/sum/sum.rs b/sum/sum.rs
index 352f1cf44..e8d7ed213 100644
--- a/sum/sum.rs
+++ b/sum/sum.rs
@@ -77,9 +77,9 @@ fn open(name: &str) -> IoResult<Box<Reader>> {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         getopts::optflag("r", "", "use the BSD compatible algorithm (default)"),
@@ -102,11 +102,11 @@ pub fn uumain(args: Vec<String>) {
         print(getopts::usage("checksum and count the blocks in a file", opts).as_slice());
         println!("");
         println!("With no FILE, or when  FILE is -, read standard input.");
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("{} {}", program, VERSION);
-        return;
+        return 0;
     }
 
     let sysv = matches.opt_present("sysv");
@@ -128,4 +128,6 @@ pub fn uumain(args: Vec<String>) {
     };
 
     println!("{} {}", sum, blocks);
+
+    return 0;
 }
diff --git a/tac/tac.rs b/tac/tac.rs
index 90307d040..19c452e4f 100644
--- a/tac/tac.rs
+++ b/tac/tac.rs
@@ -24,9 +24,9 @@ static NAME: &'static str = "tac";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     let opts = [
@@ -69,6 +69,8 @@ pub fn uumain(args: Vec<String>) {
         };
         tac(files, before, regex, separator.as_slice());
     }
+
+    return 0;
 }
 
 fn tac(filenames: Vec<String>, before: bool, _: bool, separator: &str) {
diff --git a/tee/tee.rs b/tee/tee.rs
index b4af3a42c..59013076c 100644
--- a/tee/tee.rs
+++ b/tee/tee.rs
@@ -18,19 +18,19 @@ extern crate getopts;
 use std::io::{println, stdin, stdout, Append, File, Truncate, Write};
 use std::io::{IoResult};
 use std::io::util::{copy, NullWriter, MultiWriter};
-use std::os::{args, set_exit_status};
+use std::os;
 use getopts::{getopts, optflag, usage};
 
 static NAME: &'static str = "tee";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     match options(args.as_slice()).and_then(exec) {
-        Ok(_) => set_exit_status(0),
-        Err(_) => set_exit_status(1)
+        Ok(_) => 0,
+        Err(_) => 1
     }
 }
 
@@ -153,5 +153,5 @@ fn with_path<T>(path: &Path, cb: || -> IoResult<T>) -> IoResult<T> {
 }
 
 fn warn(message: &str) {
-    error!("{}: {}", args().get(0), message);
+    error!("{}: {}", os::args().get(0), message);
 }
diff --git a/touch/touch.rs b/touch/touch.rs
index 0886e15a2..8a08f9467 100644
--- a/touch/touch.rs
+++ b/touch/touch.rs
@@ -23,9 +23,9 @@ static NAME: &'static str = "touch";
 static VERSION: &'static str = "1.0.0";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         getopts::optflag("a", "",               "change only the access time"),
         getopts::optflag("c", "no-create",      "do not create any files"),
@@ -49,7 +49,7 @@ pub fn uumain(args: Vec<String>) {
 
     if matches.opt_present("version") {
         println!("{:s} {:s}", NAME, VERSION);
-        return;
+        return 0;
     }
 
     if matches.opt_present("help") || matches.free.is_empty() {
@@ -59,7 +59,7 @@ pub fn uumain(args: Vec<String>) {
         println!("");
         println!("{:s}", getopts::usage("Update the access and modification times of \
                                          each FILE to the current time.", opts));
-        return;
+        return 0;
     }
 
     if matches.opt_present("date") && matches.opts_present(["reference".to_string(), "t".to_string()]) ||
@@ -131,6 +131,8 @@ pub fn uumain(args: Vec<String>) {
             Err(e) => fail!("Unable to modify times\n{}", e.desc)
         }
     }
+
+    return 0;
 }
 
 fn stat(path: &Path, follow: bool) -> std::io::FileStat {
diff --git a/tr/tr.rs b/tr/tr.rs
index 5b906564d..48af9ed4a 100644
--- a/tr/tr.rs
+++ b/tr/tr.rs
@@ -147,9 +147,9 @@ fn usage(opts: &[OptGroup]) {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let opts = [
         getopts::optflag("c", "complement", "use the complement of SET1"),
         getopts::optflag("C", "", "same as -c"),
@@ -162,24 +162,23 @@ pub fn uumain(args: Vec<String>) {
         Ok(m) => m,
         Err(err) => {
             show_error!(1, "{}", err.to_err_msg());
-            return;
+            return 0;
         }
     };
 
     if matches.opt_present("help") {
         usage(opts);
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("{} {}", NAME, VERSION);
-        return;
+        return 0;
     }
 
     if matches.free.len() == 0 {
         usage(opts);
-        os::set_exit_status(1);
-        return;
+        return 1;
     }
 
     let dflag = matches.opt_present("d");
@@ -188,7 +187,7 @@ pub fn uumain(args: Vec<String>) {
 
     if cflag && !dflag {
         show_error!(1, "-c is only supported with -d");
-        return;
+        return 0;
     }
 
     if dflag {
@@ -199,4 +198,6 @@ pub fn uumain(args: Vec<String>) {
         let set2 = expand_set(sets.get(1).as_slice());
         tr(set1.as_slice(), set2.as_slice());
     }
+
+    return 0;
 }
diff --git a/truncate/truncate.rs b/truncate/truncate.rs
index aada407e3..fd9f3dbea 100644
--- a/truncate/truncate.rs
+++ b/truncate/truncate.rs
@@ -47,9 +47,9 @@ enum TruncateMode {
 static NAME: &'static str = "truncate";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
 
     let opts = [
@@ -108,6 +108,8 @@ file based on its current size:
             truncate(no_create, io_blocks, reference, size, matches.free);
         }
     }
+
+    return 0;
 }
 
 fn truncate(no_create: bool, _: bool, reference: Option<String>, size: Option<String>, filenames: Vec<String>) {
diff --git a/tty/tty.rs b/tty/tty.rs
index b34ff8565..d715dd968 100644
--- a/tty/tty.rs
+++ b/tty/tty.rs
@@ -35,9 +35,9 @@ extern {
 static NAME: &'static str = "tty";
 
 #[allow(dead_code)]
-fn main () { uumain(os::args()); }
+fn main () { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let options = [
         optflag("s", "silent", "print nothing, only return an exit status")
     ];
@@ -49,7 +49,7 @@ pub fn uumain(args: Vec<String>) {
         Err(f) => {
             println(f.to_err_msg().as_slice());
             usage();
-            return
+            return 2;
         }
     };
 
@@ -71,10 +71,9 @@ pub fn uumain(args: Vec<String>) {
         }
     };
 
-    os::set_exit_status(exit_code as int);
+    return exit_code as int;
 }
 
 fn usage () {
     safe_writeln!(&mut stderr() as &mut Writer, "usage: tty [-s]");
-    os::set_exit_status(2);
 }
diff --git a/uname/uname.rs b/uname/uname.rs
index e9c4cefff..e25334275 100644
--- a/uname/uname.rs
+++ b/uname/uname.rs
@@ -52,9 +52,9 @@ unsafe fn getuname() -> utsrust {
 static NAME: &'static str = "uname";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
@@ -77,7 +77,7 @@ pub fn uumain(args: Vec<String>) {
         println!("  {:s}", program);
         println!("");
         print(getopts::usage("The uname utility writes symbols representing one or more system characteristics to the standard output.", opts).as_slice());
-        return;
+        return 0;
     }
     let uname = unsafe { getuname() };
     let mut output = String::new();
@@ -103,5 +103,7 @@ pub fn uumain(args: Vec<String>) {
         output.push_str(uname.machine.as_slice());
         output.push_str(" ");
     }
-    println!("{}", output.as_slice().trim_left())
+    println!("{}", output.as_slice().trim_left());
+
+    return 0;
 }
diff --git a/unlink/unlink.rs b/unlink/unlink.rs
index fc879bda7..4221eafa7 100644
--- a/unlink/unlink.rs
+++ b/unlink/unlink.rs
@@ -27,9 +27,9 @@ mod util;
 static NAME: &'static str = "unlink";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
@@ -50,12 +50,12 @@ pub fn uumain(args: Vec<String>) {
         println!("  {0:s} [FILE]... [OPTION]...", program);
         println!("");
         print(getopts::usage("Unlink the file at [FILE].", opts).as_slice());
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("unlink 1.0.0");
-        return;
+        return 0;
     }
 
     if matches.free.len() == 0 {
@@ -86,4 +86,6 @@ pub fn uumain(args: Vec<String>) {
             crash!(1, "cannot unlink '{0}': {1}", path.display(), e.desc);
         }
     }
+
+    return 0;
 }
diff --git a/uptime/uptime.rs b/uptime/uptime.rs
index f131fbf05..eac380d0e 100644
--- a/uptime/uptime.rs
+++ b/uptime/uptime.rs
@@ -48,9 +48,9 @@ extern {
 }
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("v", "version", "output version information and exit"),
@@ -62,7 +62,7 @@ pub fn uumain(args: Vec<String>) {
     };
     if matches.opt_present("version") {
         println!("uptime 1.0.0");
-        return;
+        return 0;
     }
     if matches.opt_present("help") || matches.free.len() > 0 {
         println!("Usage:");
@@ -71,7 +71,7 @@ pub fn uumain(args: Vec<String>) {
         print(getopts::usage("Print the current time, the length of time the system has been up,\n\
                               the number of users on the system, and the average number of jobs\n\
                               in the run queue over the last 1, 5 and 15 minutes.", opts).as_slice());
-        return;
+        return 0;
     }
 
     print_time();
@@ -80,6 +80,8 @@ pub fn uumain(args: Vec<String>) {
     print_uptime(upsecs);
     print_nusers(user_count);
     print_loadavg();
+
+    return 0;
 }
 
 fn print_loadavg() {
diff --git a/users/users.rs b/users/users.rs
index fc048153d..4017aad6f 100644
--- a/users/users.rs
+++ b/users/users.rs
@@ -48,9 +48,9 @@ extern {
 static NAME: &'static str = "users";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
@@ -69,12 +69,12 @@ pub fn uumain(args: Vec<String>) {
         println!("  {:s} [OPTION]... [FILE]", program);
         println!("");
         print(getopts::usage("Output who is currently logged in according to FILE.", opts).as_slice());
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("users 1.0.0");
-        return;
+        return 0;
     }
 
     let mut filename = DEFAULT_FILE;
@@ -83,6 +83,8 @@ pub fn uumain(args: Vec<String>) {
     }
 
     exec(filename);
+
+    return 0;
 }
 
 fn exec(filename: &str) {
diff --git a/uutils/uutils.rs b/uutils/uutils.rs
index 64fa66609..e7949d92b 100644
--- a/uutils/uutils.rs
+++ b/uutils/uutils.rs
@@ -58,9 +58,9 @@ use std::collections::hashmap::HashMap;
 static NAME: &'static str = "uutils";
 static VERSION: &'static str = "1.0.0";
 
-fn util_map() -> HashMap<&str, fn(Vec<String>)> {
-    fn uutrue(_: Vec<String>) { os::set_exit_status(0); }
-    fn uufalse(_: Vec<String>) { os::set_exit_status(1); }
+fn util_map() -> HashMap<&str, fn(Vec<String>) -> int> {
+    fn uutrue(_: Vec<String>) -> int { 0 }
+    fn uufalse(_: Vec<String>) -> int { 1 }
 
     let mut map = HashMap::new();
     map.insert("base64", base64::uumain);
@@ -108,7 +108,7 @@ fn util_map() -> HashMap<&str, fn(Vec<String>)> {
     map
 }
 
-fn usage(cmap: &HashMap<&str, fn(Vec<String>)>) {
+fn usage(cmap: &HashMap<&str, fn(Vec<String>) -> int>) {
         println!("{} {}", NAME, VERSION);
         println!("");
         println!("Usage:");
@@ -131,7 +131,7 @@ fn main() {
     let binary_as_util = binary.filename_str().unwrap();
     if umap.contains_key(&binary_as_util) {
         let &uumain = umap.get(&binary_as_util);
-        uumain(args);
+        os::set_exit_status(uumain(args));
         return
     } else if binary_as_util.starts_with("uutils")
         || binary_as_util.starts_with("busybox") {
@@ -150,7 +150,7 @@ fn main() {
         let util = args.get(0).as_slice();
         if umap.contains_key(&util) {
             let &uumain = umap.get(&util);
-            uumain(args.clone());
+            os::set_exit_status(uumain(args.clone()));
             return
         } else if args.get(0).as_slice() == "--help" {
             // see if they want help on a specific util
@@ -158,7 +158,7 @@ fn main() {
                 let util = args.get(1).as_slice();
                 if umap.contains_key(&util) {
                     let &uumain = umap.get(&util);
-                    uumain(vec!["--help".to_string()]);
+                    os::set_exit_status(uumain(vec!["--help".to_string()]));
                     return
                 } else {
                     println!("{}: applet not found", util);
@@ -167,6 +167,7 @@ fn main() {
                 }
             }
             usage(&umap);
+            os::set_exit_status(0);
             return
         } else {
             println!("{}: applet not found", util);
@@ -176,6 +177,7 @@ fn main() {
     } else {
         // no arguments provided
         usage(&umap);
+        os::set_exit_status(0);
         return
     }
 }
diff --git a/wc/wc.rs b/wc/wc.rs
index 9bf76cde2..bfd4d1597 100644
--- a/wc/wc.rs
+++ b/wc/wc.rs
@@ -34,9 +34,9 @@ struct Result {
 static NAME: &'static str = "wc";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("c", "bytes", "print the byte counts"),
@@ -62,12 +62,12 @@ pub fn uumain(args: Vec<String>) {
         print(getopts::usage("Print newline, word and byte counts for each FILE", opts).as_slice());
         println!("");
         println!("With no FILE, or when FILE is -, read standard input.");
-        return;
+        return 0;
     }
 
     if matches.opt_present("version") {
         println!("wc 1.0.0");
-        return;
+        return 0;
     }
 
     let mut files = matches.free.clone();
@@ -76,6 +76,8 @@ pub fn uumain(args: Vec<String>) {
     }
 
     wc(files, &matches);
+
+    return 0;
 }
 
 static CR: u8 = '\r' as u8;
diff --git a/whoami/whoami.rs b/whoami/whoami.rs
index de5fe345c..65deb2d13 100644
--- a/whoami/whoami.rs
+++ b/whoami/whoami.rs
@@ -42,9 +42,9 @@ unsafe fn getusername() -> String {
 static NAME: &'static str = "whoami";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).as_slice();
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
@@ -61,14 +61,16 @@ pub fn uumain(args: Vec<String>) {
         println!("  {:s}", program);
         println!("");
         print(getopts::usage("print effective userid", opts).as_slice());
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("whoami 1.0.0");
-        return;
+        return 0;
     }
 
     exec();
+
+    return 0;
 }
 
 pub fn exec() {
diff --git a/yes/yes.rs b/yes/yes.rs
index b03b9ae5c..38d0276b5 100644
--- a/yes/yes.rs
+++ b/yes/yes.rs
@@ -25,9 +25,9 @@ mod util;
 static NAME: &'static str = "yes";
 
 #[allow(dead_code)]
-fn main() { uumain(os::args()); }
+fn main() { os::set_exit_status(uumain(os::args())); }
 
-pub fn uumain(args: Vec<String>) {
+pub fn uumain(args: Vec<String>) -> int {
     let program = args.get(0).clone();
     let opts = [
         getopts::optflag("h", "help", "display this help and exit"),
@@ -46,11 +46,11 @@ pub fn uumain(args: Vec<String>) {
         println!("  {0:s} [STRING]... [OPTION]...", program);
         println!("");
         print(getopts::usage("Repeatedly output a line with all specified STRING(s), or 'y'.", opts).as_slice());
-        return;
+        return 0;
     }
     if matches.opt_present("version") {
         println!("yes 1.0.0");
-        return;
+        return 0;
     }
     let mut string = "y".to_string();
     if !matches.free.is_empty() {
@@ -58,6 +58,8 @@ pub fn uumain(args: Vec<String>) {
     }
 
     exec(string.as_slice());
+
+    return 0;
 }
 
 pub fn exec(string: &str) {