Add support for --no-shell option

src/cli.rs

@@ -14,6 +14,7 @@ pub struct Args {
     pub restart: bool,
     pub debug: bool,
     pub run_initially: bool,
+    pub no_shell: bool,
     pub no_vcs_ignore: bool,
     pub once: bool,
     pub poll: bool,
@@ -102,6 +103,10 @@ pub fn get_args() -> Args {
                  .help("Forces polling mode")
                  .long("force-poll")
                  .value_name("interval"))
+        .arg(Arg::with_name("no-shell")
+                 .help("Do not wrap command in 'sh -c'")
+                 .short("n")
+                 .long("no-shell"))
         .arg(Arg::with_name("once").short("1").hidden(true))
         .get_matches();
 
@@ -164,6 +169,7 @@ pub fn get_args() -> Args {
         restart: args.is_present("restart"),
         debug: args.is_present("debug"),
         run_initially: !args.is_present("postpone"),
+        no_shell: args.is_present("no-shell"),
         no_vcs_ignore: args.is_present("no-vcs-ignore"),
         once: args.is_present("once"),
         poll: args.occurrences_of("poll") > 0,

src/main.rs

@@ -107,7 +107,7 @@ fn main() {
         }
 
         let mut guard = child_process.write().unwrap();
-        *guard = Some(process::spawn(&args.cmd, vec![]));
+        *guard = Some(process::spawn(&args.cmd, vec![], args.no_shell));
     }
 
     loop {
@@ -140,7 +140,7 @@ fn main() {
                 debug!("Launching child process");
                 {
                     let mut guard = child_process.write().unwrap();
-                    *guard = Some(process::spawn(&args.cmd, paths));
+                    *guard = Some(process::spawn(&args.cmd, paths, args.no_shell));
                 }
             }
 
@@ -158,7 +158,7 @@ fn main() {
                 debug!("Launching child process");
                 {
                     let mut guard = child_process.write().unwrap();
-                    *guard = Some(process::spawn(&args.cmd, paths));
+                    *guard = Some(process::spawn(&args.cmd, paths, args.no_shell));
                 }
             }
 
@@ -179,7 +179,7 @@ fn main() {
                 debug!("Launching child process");
                 {
                     let mut guard = child_process.write().unwrap();
-                    *guard = Some(process::spawn(&args.cmd, paths));
+                    *guard = Some(process::spawn(&args.cmd, paths, args.no_shell));
                 }
             }
         }

src/process.rs

@@ -1,7 +1,7 @@
 use std::path::PathBuf;
 
-pub fn spawn(cmd: &str, updated_paths: Vec<PathBuf>) -> Process {
-    self::imp::Process::new(cmd, updated_paths).expect("unable to spawn process")
+pub fn spawn(cmd: &str, updated_paths: Vec<PathBuf>, no_shell: bool) -> Process {
+    self::imp::Process::new(cmd, updated_paths, no_shell).expect("unable to spawn process")
 }
 
 pub use self::imp::Process;
@@ -24,13 +24,33 @@ mod imp {
     #[allow(unknown_lints)]
     #[allow(mutex_atomic)]
     impl Process {
-        pub fn new(cmd: &str, updated_paths: Vec<PathBuf>) -> Result<Process> {
+        pub fn new(cmd: &str, updated_paths: Vec<PathBuf>, no_shell: bool) -> Result<Process> {
             use nix::unistd::*;
             use std::io;
             use std::os::unix::process::CommandExt;
 
-            let mut command = Command::new("sh");
-            command.arg("-c").arg(cmd);
+            // Assemble command to run.
+            // This is either the first argument from cmd (if no_shell was given) or "sh".
+            // Using "sh -c" gives us features like supportin pipes and redirects,
+            // but is a little less performant and can cause trouble when using custom signals
+            // (e.g. --signal SIGHUP)
+            let mut iter_args = cmd.split_whitespace();
+            let arg0 = match no_shell {
+                true => iter_args.next().unwrap(),
+                false => "sh",
+            };
+
+            // TODO: There might be a better way of doing this with &str.
+            //       I've had to fall back to String, as I wasn't able to join(" ") a Vec<&str>
+            //       into a &str
+            let args: Vec<String> = match no_shell {
+                true => iter_args.map(str::to_string).collect(),
+                false => vec!["-c".to_string(), iter_args.collect::<Vec<&str>>().join(" ")],
+            };
+
+            let mut command = Command::new(arg0);
+            command.args(args);
+            debug!("Assembled command {:?}", command);
 
             if let Some(single_path) = super::get_single_updated_path(&updated_paths) {
                 command.env("WATCHEXEC_UPDATED_PATH", single_path);