From 8ff9dd1e2537b4e9a84af49699a1d2f19201e68d Mon Sep 17 00:00:00 2001
From: Diomidis Spinellis <dds@aueb.gr>
Date: Sun, 10 Aug 2025 01:29:38 +0300
Subject: [PATCH] Implement silent comment command

---
 src/uu/sed/src/compiler.rs                  | 20 ++++++++++++++++++--
 tests/by-util/test_sed.rs                   |  6 ++++++
 tests/fixtures/sed/output/comment           |  1 +
 tests/fixtures/sed/output/comment_no_silent | 15 +++++++++++++++
 tests/fixtures/sed/output/comment_silent    |  1 +
 5 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 tests/fixtures/sed/output/comment
 create mode 100644 tests/fixtures/sed/output/comment_no_silent
 create mode 100644 tests/fixtures/sed/output/comment_silent

diff --git a/src/uu/sed/src/compiler.rs b/src/uu/sed/src/compiler.rs
index 3db8e78a..a7102d84 100644
--- a/src/uu/sed/src/compiler.rs
+++ b/src/uu/sed/src/compiler.rs
@@ -78,7 +78,6 @@ pub fn compile(
     }
     patch_block_endings(result.clone());
 
-    // TODO: setup append & match structures
     Ok(result)
 }
 
@@ -229,8 +228,25 @@ fn compile_sequence(
 
     loop {
         line.eat_spaces();
+
+        // According to POSIX: "If the first two characters in the script are
+        // "#n", the default output shall be suppressed".
+        if !line.eol()
+            && line.current() == '#'
+            && lines.get_line_number() == 1
+            && line.get_pos() == 0
+        {
+            line.advance();
+            if !line.eol() && line.current() == 'n' {
+                context.quiet = true;
+            }
+            // Ignore rest of line
+            while !line.eol() {
+                line.advance();
+            }
+        }
+
         if line.eol() || line.current() == '#' {
-            // TODO: set context.quiet for StringVal starting with #n
             match lines.next_line()? {
                 None => {
                     return Ok(head);
diff --git a/tests/by-util/test_sed.rs b/tests/by-util/test_sed.rs
index 5a8b0db7..e44fb968 100644
--- a/tests/by-util/test_sed.rs
+++ b/tests/by-util/test_sed.rs
@@ -154,6 +154,12 @@ const LINES1: &str = "input/lines1";
 const LINES2: &str = "input/lines2";
 const NO_NEW_LINE: &str = "input/no-new-line.txt";
 
+////////////////////////////////////////////////////////////
+// Comments
+check_output!(comment, ["-n", "-e", "4p;# comment", LINES1]);
+check_output!(comment_silent, ["-e", "#n", "-e", "4p", LINES1]);
+check_output!(comment_no_silent, ["-e", "4p;#n comment", LINES1]);
+
 ////////////////////////////////////////////////////////////
 // Address ranges: One and two, numeric and pattern
 check_output!(addr_one_line, ["-n", "-e", "4p", LINES1]);
diff --git a/tests/fixtures/sed/output/comment b/tests/fixtures/sed/output/comment
new file mode 100644
index 00000000..a7c92f0e
--- /dev/null
+++ b/tests/fixtures/sed/output/comment
@@ -0,0 +1 @@
+l1_4
diff --git a/tests/fixtures/sed/output/comment_no_silent b/tests/fixtures/sed/output/comment_no_silent
new file mode 100644
index 00000000..ccaabc22
--- /dev/null
+++ b/tests/fixtures/sed/output/comment_no_silent
@@ -0,0 +1,15 @@
+l1_1
+l1_2
+l1_3
+l1_4
+l1_4
+l1_5
+l1_6
+l1_7
+l1_8
+l1_9
+l1_10
+l1_11
+l1_12
+l1_13
+l1_14
diff --git a/tests/fixtures/sed/output/comment_silent b/tests/fixtures/sed/output/comment_silent
new file mode 100644
index 00000000..a7c92f0e
--- /dev/null
+++ b/tests/fixtures/sed/output/comment_silent
@@ -0,0 +1 @@
+l1_4