feat: add the tee command

coreutils/src/commands/mod.rs

@@ -19,3 +19,4 @@ command!(pwd::Pwd);
 command!(sleep::Sleep);
 command!(whoami::WhoAmI);
 command!(hostname::Hostname);
+command!(tee::Tee);

coreutils/src/commands/tee.rs

@@ -0,0 +1,50 @@
+use boxutils::args::ArgParser;
+use boxutils::commands::Command;
+use std::fs::OpenOptions;
+use std::io::Write;
+
+// TODO: Add the -i flag to ignore SIGINT.
+//       Not done yet because we want this to be
+//       Windows-compatible
+
+pub struct Tee;
+
+impl Command for Tee {
+    fn execute(&self) {
+        let args = ArgParser::builder()
+            .add_flag("--help")
+            .add_flag("-a")
+            .parse_args("tee");
+
+        if args.get_flag("--help") {
+            println!("Usage: tee -a [FILE]...");
+        }
+
+        let append = args.get_flag("-a");
+        let files = args.get_normal_args();
+        let mut writes: Vec<Box<dyn Write>> = vec![Box::new(std::io::stdout())];
+
+        for file in files {
+            let this_file = OpenOptions::new()
+                .create(true)
+                .write(true)
+                .append(append)
+                .open(&file);
+
+            if let Ok(this_file) = this_file {
+                writes.push(Box::new(this_file));
+            } else {
+                eprintln!("tee: unable to open file: {}", file);
+            }
+        }
+
+        let mut buffer = String::new();
+        while std::io::stdin().read_line(&mut buffer).unwrap_or(0) > 0 {
+            for output in &mut writes {
+                let _ = output.write_all(buffer.as_bytes());
+                let _ = output.flush();
+            }
+            buffer.clear();
+        }
+    }
+}

src/registry.rs

@@ -29,6 +29,7 @@ pub fn get_registry() -> CommandRegistry {
         "sleep" => coreutils::commands::Sleep,
         "whoami" => coreutils::commands::WhoAmI,
         "hostname" => coreutils::commands::Hostname,
+        "tee" => coreutils::commands::Tee,
         "box" => Boxcmd
     });