From a0d628898226e272e9f29137da148991e07f3641 Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <sebastian.thiel@icloud.com>
Date: Sat, 29 May 2021 13:13:49 +0800
Subject: Only display progress on if stderr is a tty

---
 src/aggregate.rs | 32 ++++++++++++++++++--------------
 src/main.rs      | 19 +++++++++++--------
 2 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/src/aggregate.rs b/src/aggregate.rs
index 8087060..5ff530b 100644
--- a/src/aggregate.rs
+++ b/src/aggregate.rs
@@ -19,7 +19,7 @@ use std::{
 /// If `sort_by_size_in_bytes` is set, we will sort all sizes (ascending) before outputting them.
 pub fn aggregate(
     mut out: impl io::Write,
-    mut err: impl io::Write + Send + 'static,
+    err: Option<impl io::Write + Send + 'static>,
     walk_options: WalkOptions,
     compute_total: bool,
     sort_by_size_in_bytes: bool,
@@ -36,19 +36,23 @@ pub fn aggregate(
     let mut inodes = InodeFilter::default();
     let paths: Vec<_> = paths.into_iter().collect();
     let shared_count = Arc::new(AtomicU64::new(0));
-    thread::spawn({
-        let shared_count = Arc::clone(&shared_count);
-        thread::sleep(Duration::from_secs(1));
-        move || loop {
-            thread::sleep(Duration::from_millis(100));
-            write!(
-                err,
-                "Enumerating {} entries\r",
-                shared_count.load(Ordering::Relaxed)
-            )
-            .ok();
-        }
-    });
+
+    if let Some(mut err) = err {
+        thread::spawn({
+            let shared_count = Arc::clone(&shared_count);
+            thread::sleep(Duration::from_secs(1));
+            move || loop {
+                thread::sleep(Duration::from_millis(100));
+                write!(
+                    err,
+                    "Enumerating {} entries\r",
+                    shared_count.load(Ordering::Relaxed)
+                )
+                .ok();
+            }
+        });
+    }
+
     for path in paths.into_iter() {
         num_roots += 1;
         let mut num_bytes = 0u128;
diff --git a/src/main.rs b/src/main.rs
index f8cdabc..aa9d82e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,18 +2,21 @@
 use anyhow::Result;
 use clap::Clap;
 use dua::{ByteFormat, TraversalSorting};
-use std::{
-    fs, io,
-    io::{stderr, Write},
-    path::PathBuf,
-    process,
-};
+use std::{fs, io, io::Write, path::PathBuf, process};
 
 mod crossdev;
 #[cfg(any(feature = "tui-unix", feature = "tui-crossplatform"))]
 mod interactive;
 mod options;
 
+fn stderr_if_tty() -> Option<io::Stderr> {
+    if atty::is(atty::Stream::Stderr) {
+        Some(io::stderr())
+    } else {
+        None
+    }
+}
+
 fn main() -> Result<()> {
     use options::Command::*;
 
@@ -72,7 +75,7 @@ fn main() -> Result<()> {
             let stdout_locked = stdout.lock();
             let (res, stats) = dua::aggregate(
                 stdout_locked,
-                stderr(),
+                stderr_if_tty(),
                 walk_options,
                 !no_total,
                 !no_sort,
@@ -88,7 +91,7 @@ fn main() -> Result<()> {
             let stdout_locked = stdout.lock();
             dua::aggregate(
                 stdout_locked,
-                stderr(),
+                stderr_if_tty(),
                 walk_options,
                 true,
                 true,
-- 
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