sleep: use pause

Signed-off-by: Tamerlan Salkenov <catamana@proton.me>

Author: tsalkenov

Cargo.lock

@@ -21,6 +21,7 @@ path = "src/sleep.rs"
 clap = { workspace = true }
 uucore = { workspace = true, features = ["parser"] }
 fluent = { workspace = true }
+nix = { workspace = true }
 
 [[bin]]
 name = "sleep"

src/uu/sleep/Cargo.toml

@@ -4,6 +4,7 @@
 // file that was distributed with this source code.
 
 use clap::{Arg, ArgAction, Command};
+use nix::unistd::pause;
 use std::thread;
 use std::time::Duration;
 use uucore::translate;
@@ -70,6 +71,10 @@ fn sleep(args: &[&str]) -> UResult<()> {
     if arg_error {
         return Err(UUsageError::new(1, ""));
     }
-    thread::sleep(sleep_dur);
+    if sleep_dur == Duration::MAX {
+        pause();
+    } else {
+        thread::sleep(sleep_dur);
+    }
     Ok(())
 }