ps: Add --quick-pid option

src/uu/ps/src/process_selection.rs

@@ -49,6 +49,8 @@ pub struct ProcessSelectionSettings {
 
     /// - `-C` Select by command name
     pub command_names: Option<HashSet<String>>,
+    /// - `-q, --quick-pid` Quick process selection by PID
+    pub quick_pids: Option<HashSet<usize>>,
     /// - `-p, --pid` Select specific process IDs
     pub pids: Option<HashSet<usize>>,
     /// - `--ppid` Select specific parent process IDs
@@ -81,6 +83,9 @@ impl ProcessSelectionSettings {
             command_names: matches
                 .get_many::<Vec<String>>("command")
                 .map(|xs| xs.flatten().cloned().collect()),
+            quick_pids: matches
+                .get_many::<Vec<usize>>("quick-pid")
+                .map(|xs| xs.flatten().copied().collect()),
             pids: matches
                 .get_many::<Vec<usize>>("pid")
                 .map(|xs| xs.flatten().copied().collect()),
@@ -108,6 +113,18 @@ impl ProcessSelectionSettings {
     }
 
     pub fn select_processes(self) -> UResult<Vec<ProcessInformation>> {
+        if let Some(ref quick_pids) = self.quick_pids {
+            let mut selected = Vec::new();
+            for &pid in quick_pids {
+                if let Ok(process) =
+                    ProcessInformation::try_new(std::path::PathBuf::from(format!("/proc/{}", pid)))
+                {
+                    selected.push(process);
+                }
+            }
+            return Ok(selected);
+        }
+
         let mut current_process = ProcessInformation::current_process_info().unwrap();
         let current_tty = current_process.tty();
         let current_euid = current_process.euid().unwrap();

src/uu/ps/src/ps.rs

@@ -379,12 +379,12 @@ pub fn uu_app() -> Command {
                 .value_parser(parse_uid_list)
                 .help("select by effective user ID (EUID) or name"),
         )
-    // .args([
-    //     Arg::new("pPID").long("ppid").help("parent process id"),
-    //     Arg::new("qPID")
-    //         .short('q')
-    //         .long("quick-pid")
-    //         .help("process id"),
-    //     Arg::new("t").short('t').long("tty").help("terminal"),
-    // ])
+        .arg(
+            Arg::new("quick-pid")
+                .short('q')
+                .long("quick-pid")
+                .action(ArgAction::Append)
+                .value_parser(parse_numeric_list)
+                .help("quick process selection by PID"),
+        )
 }

tests/by-util/test_ps.rs

@@ -230,7 +230,7 @@ fn test_command_name_selection() {
 
 #[test]
 #[cfg(target_os = "linux")]
-fn test_pid_selection() {
+fn test_pid_and_quick_pid_selection() {
     let our_pid = std::process::id();
     // Test that only pid 1 and pid of the test runner is present
     let test = |pid_args: &[&str]| {
@@ -243,24 +243,24 @@ fn test_pid_selection() {
             .stdout_matches(&match_regex);
     };
 
-    for flag in ["-p", "--pid"] {
+    for flag in ["-p", "--pid", "-q", "--quick-pid"] {
         test(&[flag, &format!("1 {our_pid}")]);
         test(&[flag, &format!("1,{our_pid}")]);
         test(&[flag, "1", flag, &our_pid.to_string()]);
-    }
 
-    // Test nonexistent PID
-    new_ucmd!()
-        .args(&["-p", "0", "--no-headers"])
-        .fails()
-        .code_is(1)
-        .no_output();
+        // Test nonexistent PID
+        new_ucmd!()
+            .args(&[flag, "0", "--no-headers"])
+            .fails()
+            .code_is(1)
+            .no_output();
 
-    // Test invalid PID
-    new_ucmd!()
-        .args(&["-p", "invalid"])
-        .fails()
-        .stderr_contains("invalid number");
+        // Test invalid PID
+        new_ucmd!()
+            .args(&[flag, "invalid"])
+            .fails()
+            .stderr_contains("invalid number");
+    }
 }
 
 #[test]