add renice

src/uu/renice/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "uu_renice"
+version = "0.0.1"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = { workspace = true }
+
+[[bin]]
+name = "renice"
+path = "src/renice.rs"

src/uu/renice/src/renice.rs

@@ -0,0 +1,34 @@
+    use std::env;
+    use std::process;
+    use std::str::FromStr;
+use libc::{c_char, c_int, execvp, PRIO_PROCESS};
+use std::io::{Error, Write};
+
+
+    fn main() {
+        let args: Vec<String> = env::args().collect();
+
+        if args.len() != 3 {
+            eprintln!("Usage: renice <nice value> <pid>");
+            process::exit(1);
+        }
+
+        let nice_value = i32::from_str(&args[1]).unwrap_or_else(|_| {
+            eprintln!("Invalid nice value");
+            process::exit(1);
+        });
+
+        let pid = i32::from_str(&args[2]).unwrap_or_else(|_| {
+            eprintln!("Invalid PID");
+	    process::exit(1);
+        });
+
+    if unsafe { libc::setpriority(PRIO_PROCESS, pid.try_into().unwrap(), nice_value) } == -1 {
+       eprintln!("Failed to set nice value: {}",             Error::last_os_error());
+       process::exit(1);
+   }
+
+   println!("Nice value of process {} set to {}", pid, nice_value);
+
+}
+