it works now

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "see"
+name = "seep"
 version = "0.1.0"
 edition = "2021"
 publish = true
@@ -7,10 +7,8 @@ authors = ["Christoph J. Scherr <software@cscherr.de>"]
 license = "MIT"
 description = "print stdin to terminal, then to stdout (for piping)"
 readme = "README.md"
-homepage = "https://git.cscherr.de/PlexSheep/see"
-repository = "https://git.cscherr.de/PlexSheep/see"
+homepage = "https://git.cscherr.de/PlexSheep/seep"
+repository = "https://git.cscherr.de/PlexSheep/seep"
 keywords = ["cli"]
 
-
 [dependencies]
-

README.md

@@ -1,3 +1,3 @@
-# see
+# seep
 
-print stdin to terminal, then pipe into next process
+print stdin to terminal, then pipe into next process

src/main.rs

@@ -1,15 +1,30 @@
 use std::io::{self, prelude::*};
+const TTY: &str = "/dev/tty";
 
 fn main() -> Result<(), io::Error> {
-    // TODO: check if stdin is empty and show usage
+    // /dev/tty points the currently opened terminal. If we write to it directly, we bypass piping
+    // to the next process
     let mut tty = std::fs::File::options()
         .write(true)
         .read(false)
-        .open("/dev/tty")
+        // try to use $TTY set by the terminal, otherwise use the default tty
+        .open(std::env::var("TTY").unwrap_or(String::from(TTY)))
         .inspect_err(|err| eprintln!("{err}"))?;
-    // FIXME: only works with cargo run?
-    io::copy(&mut io::stdin(), &mut tty).inspect_err(|err| eprintln!("{err}"))?;
-    tty.flush().inspect_err(|err| eprintln!("{err}"))?;
-    io::copy(&mut io::stdin(), &mut io::stdout()).inspect_err(|err| eprintln!("{err}"))?;
+    // we want to write to the stdout too
+    let mut stdout = io::stdout();
+    // sadly, we need to store the content of `stdin` in a buffer and cannot just `io::copy()` it
+    // multiple times. `tee` from the GNU coreutils does this too.
+    let mut buf = Vec::new();
+    io::stdin()
+        .read_to_end(&mut buf)
+        .inspect_err(|err| eprintln!("{err}"))?;
+
+    // now we just write to our targets
+    tty.write_all(&buf).inspect_err(|err| eprintln!("{err}"))?;
+    tty.flush().inspect_err(|err| eprintln!("{err}"))?; // make sure it comes there
+    stdout
+        .write_all(&buf)
+        .inspect_err(|err| eprintln!("{err}"))?;
+    stdout.flush().inspect_err(|err| eprintln!("{err}"))?; // make sure it comes there
     Ok(())
 }

tests/cli.rs

@@ -1,4 +0,0 @@
-#[test]
-fn pipe_echo_cat() {
-    todo!()
-}