Add "shell" option to config

This allows you to configure the shell to use when alacritty starts.

cc: #122

alacritty.yml

@@ -192,3 +192,8 @@ key_bindings:
 mouse_bindings:
   - { mouse: Middle, action: PasteSelection }
 
+
+# Shell
+#
+# You can set this to a path to your favorite shell, e.g. /bin/fish
+shell:

alacritty_macos.yml

@@ -192,3 +192,7 @@ key_bindings:
 mouse_bindings:
   - { mouse: Middle, action: PasteSelection }
 
+# Shell
+#
+# You can set this to a path to your favorite shell, e.g. /bin/fish
+shell:

src/config.rs

@@ -196,6 +196,8 @@ pub struct Config {
     #[serde(default="default_mouse_bindings")]
     mouse_bindings: Vec<MouseBinding>,
 
+    shell: Option<PathBuf>,
+
     /// Path where config was loaded from
     config_path: Option<PathBuf>,
 }
@@ -228,6 +230,7 @@ impl Default for Config {
             colors: Default::default(),
             key_bindings: Vec::new(),
             mouse_bindings: Vec::new(),
+            shell: None,
             config_path: None,
         }
     }
@@ -878,6 +881,12 @@ impl Config {
             .map(|p| p.as_path())
     }
 
+    pub fn shell(&self) -> Option<&Path> {
+        self.shell
+            .as_ref()
+            .map(|p| p.as_path())
+    }
+
     fn load_from<P: Into<PathBuf>>(path: P) -> Result<Config> {
         let path = path.into();
         let raw = Config::read_file(path.as_path())?;

src/main.rs

@@ -93,7 +93,7 @@ fn run(mut config: Config, options: cli::Options) -> Result<(), Box<Error>> {
     // The pty forks a process to run the shell on the slave side of the
     // pseudoterminal. A file descriptor for the master side is retained for
     // reading/writing to the shell.
-    let mut pty = tty::new(display.size());
+    let mut pty = tty::new(&config, display.size());
 
     // Create the pseudoterminal I/O loop
     //

src/tty.rs

@@ -25,6 +25,7 @@ use libc::{self, winsize, c_int, pid_t, WNOHANG, WIFEXITED, WEXITSTATUS, SIGCHLD
 
 use term::SizeInfo;
 use display::OnResize;
+use config::Config;
 
 /// Process ID of child process
 ///
@@ -202,14 +203,19 @@ fn get_pw_entry(buf: &mut [i8; 1024]) -> Passwd {
 }
 
 /// Exec a shell
-fn execsh() -> ! {
+fn execsh(config: &Config) -> ! {
     let mut buf = [0; 1024];
     let pw = get_pw_entry(&mut buf);
 
+    let shell = match config.shell() {
+        Some(shell) => shell.to_str().unwrap(),
+        None => pw.shell
+    };
+
     // setup environment
     env::set_var("LOGNAME", pw.name);
     env::set_var("USER", pw.name);
-    env::set_var("SHELL", pw.shell);
+    env::set_var("SHELL", shell);
     env::set_var("HOME", pw.dir);
     env::set_var("TERM", "xterm-256color"); // sigh
 
@@ -223,7 +229,7 @@ fn execsh() -> ! {
     }
 
     // pw.shell is null terminated
-    let shell = unsafe { CStr::from_ptr(pw.shell.as_ptr() as *const _) };
+    let shell = unsafe { CStr::from_ptr(shell.as_ptr() as *const _) };
 
     let argv = [shell.as_ptr(), ptr::null()];
 
@@ -239,7 +245,7 @@ fn execsh() -> ! {
 }
 
 /// Create a new tty and return a handle to interact with it.
-pub fn new<T: ToWinsize>(size: T) -> Pty {
+pub fn new<T: ToWinsize>(config: &Config, size: T) -> Pty {
     let win = size.to_winsize();
 
     let (master, slave) = openpty(win.ws_row as _, win.ws_col as _);
@@ -265,7 +271,7 @@ pub fn new<T: ToWinsize>(size: T) -> Pty {
             }
 
             // Exec a shell!
-            execsh();
+            execsh(config);
         },
         Relation::Parent(pid) => {
             unsafe {