add musl utmpx limitation to --help texts

Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>

src/uu/pinky/src/pinky.rs

@@ -10,7 +10,18 @@ use uucore::{format_usage, help_about, help_usage};
 
 mod platform;
 
+#[cfg(target_env = "musl")]
+const ABOUT: &str = concat!(
+    help_about!("pinky.md"),
+    "\n\nWarning: When built with musl libc, the `pinky` utility may show incomplete \n",
+    "or missing user information due to musl's stub implementation of `utmpx` \n",
+    "functions. This limitation affects the ability to retrieve accurate details \n",
+    "about logged-in users."
+);
+
+#[cfg(not(target_env = "musl"))]
 const ABOUT: &str = help_about!("pinky.md");
+
 const USAGE: &str = help_usage!("pinky.md");
 
 mod options {

src/uu/uptime/src/uptime.rs

@@ -23,7 +23,17 @@ use uucore::{format_usage, help_about, help_usage};
 #[cfg(not(target_os = "openbsd"))]
 use uucore::utmpx::*;
 
+#[cfg(target_env = "musl")]
+const ABOUT: &str = concat!(
+    help_about!("uptime.md"),
+    "\n\nWarning: When built with musl libc, the `uptime` utility may show '0 users' \n",
+    "due to musl's stub implementation of utmpx functions. Boot time and load averages \n",
+    "are still calculated using alternative mechanisms."
+);
+
+#[cfg(not(target_env = "musl"))]
 const ABOUT: &str = help_about!("uptime.md");
+
 const USAGE: &str = help_usage!("uptime.md");
 pub mod options {
     pub static SINCE: &str = "since";

src/uu/users/src/users.rs

@@ -18,7 +18,16 @@ use utmp_classic::{UtmpEntry, parse_from_path};
 #[cfg(not(target_os = "openbsd"))]
 use uucore::utmpx::{self, Utmpx};
 
+#[cfg(target_env = "musl")]
+const ABOUT: &str = concat!(
+    help_about!("users.md"),
+    "\n\nWarning: When built with musl libc, the `users` utility may show '0 users' \n",
+    "due to musl's stub implementation of utmpx functions."
+);
+
+#[cfg(not(target_env = "musl"))]
 const ABOUT: &str = help_about!("users.md");
+
 const USAGE: &str = help_usage!("users.md");
 
 #[cfg(target_os = "openbsd")]

src/uu/who/src/who.rs

@@ -28,7 +28,17 @@ mod options {
     pub const FILE: &str = "FILE"; // if length=1: FILE, if length=2: ARG1 ARG2
 }
 
+#[cfg(target_env = "musl")]
+const ABOUT: &str = concat!(
+    help_about!("who.md"),
+    "\n\nNote: When built with musl libc, the `who` utility will not display any \n",
+    "information about logged-in users. This is due to musl's stub implementation \n",
+    "of `utmpx` functions, which prevents access to the necessary data."
+);
+
+#[cfg(not(target_env = "musl"))]
 const ABOUT: &str = help_about!("who.md");
+
 const USAGE: &str = help_usage!("who.md");
 
 #[cfg(target_os = "linux")]