The -t flag now works when the tmux session already exists (fix #54)

src/tmux.rs

@@ -5,7 +5,9 @@ use super::utils::{Check, PathExt};
 use directories::BaseDirs;
 use failure::Error;
 use std::env;
+use std::io;
 use std::os::unix::process::CommandExt;
+use std::path::Path;
 use std::process::Command;
 
 pub fn run_tpm(base_dirs: &BaseDirs, terminal: &mut Terminal, dry_run: bool) -> Option<(&'static str, bool)> {
@@ -27,23 +29,50 @@ pub fn run_tpm(base_dirs: &BaseDirs, terminal: &mut Terminal, dry_run: bool) ->
     None
 }
 
+fn has_session(tmux: &Path, session_name: &str) -> Result<bool, io::Error> {
+    Ok(Command::new(tmux)
+        .args(&["has-session", "-t", session_name])
+        .spawn()?
+        .wait()?
+        .success())
+}
+
+fn run_in_session(tmux: &Path, command: &str) -> Result<(), Error> {
+    Command::new(tmux)
+        .args(&["new-window", "-a", "-t", "topgrade:1", command])
+        .spawn()?
+        .wait()?
+        .check()?;
+
+    Ok(())
+}
+
 pub fn run_in_tmux() -> ! {
     let tmux = which("tmux").expect("Could not find tmux");
+    let command = env::args().collect::<Vec<String>>().join(" ");
 
-    let err = Command::new(tmux)
-        .args(&[
-            "new-session",
-            "-s",
-            "topgrade",
-            "-n",
-            "topgrade",
-            &env::args().collect::<Vec<String>>().join(" "),
-            ";",
-            "set",
-            "remain-on-exit",
-            "on",
-        ])
-        .exec();
+    if has_session(&tmux, "topgrade").expect("Error launching tmux") {
+        run_in_session(&tmux, &command).expect("Error launching tmux");
 
-    panic!("{:?}", err);
+        let err = Command::new(tmux).args(&["attach", "-t", "topgrade"]).exec();
+
+        panic!("{:?}", err);
+    } else {
+        let err = Command::new(tmux)
+            .args(&[
+                "new-session",
+                "-s",
+                "topgrade",
+                "-n",
+                "topgrade",
+                &command,
+                ";",
+                "set",
+                "remain-on-exit",
+                "on",
+            ])
+            .exec();
+
+        panic!("{:?}", err);
+    }
 }