vmstat: implement --timestamp

src/uu/vmstat/Cargo.toml

@@ -12,9 +12,10 @@ version.workspace = true
 
 [dependencies]
 bytesize = { workspace = true }
+chrono = { workspace = true, default-features = false, features = ["clock"] }
 clap = { workspace = true }
 terminal_size = { workspace = true }
-uucore = { workspace = true }
+uucore = { workspace = true, features = ["custom-tz-fmt"] }
 
 [lib]
 path = "src/vmstat.rs"

src/uu/vmstat/src/picker.rs

@@ -17,7 +17,7 @@ pub type Picker = (
 #[cfg(target_os = "linux")]
 pub fn get_pickers(matches: &ArgMatches) -> Vec<Picker> {
     let wide = matches.get_flag("wide");
-    vec![
+    let mut pickers = vec![
         concat_helper(
             if wide {
                 ("--procs--".into(), "   r    b".into())
@@ -62,7 +62,18 @@ pub fn get_pickers(matches: &ArgMatches) -> Vec<Picker> {
             },
             get_cpu_info,
         ),
-    ]
+    ];
+    if matches.get_flag("timestamp") {
+        pickers.push(concat_helper(
+            (
+                "-----timestamp-----".into(),
+                format!("{:>19}", uucore::custom_tz_fmt::custom_time_format("%Z")),
+            ),
+            get_timestamp,
+        ));
+    }
+
+    pickers
 }
 
 #[cfg(target_os = "linux")]
@@ -267,3 +278,15 @@ fn get_cpu_info(
         (len, format!("{:.0}", cpu_load.guest)),
     ]
 }
+
+#[cfg(target_os = "linux")]
+fn get_timestamp(
+    _proc_data: &ProcData,
+    _proc_data_before: Option<&ProcData>,
+    _matches: &ArgMatches,
+) -> Vec<(usize, String)> {
+    vec![(
+        10,
+        chrono::Local::now().format("%Y-%m-%d %H:%M:%S").to_string(),
+    )]
+}

src/uu/vmstat/src/vmstat.rs

@@ -133,7 +133,7 @@ pub fn uu_app() -> Command {
             // arg!(-D --"disk-sum" "Report some summary statistics about disk activity"),
             // arg!(-p --partition <device> "Detailed statistics about partition"),
             arg!(-S --unit <character> "Switches outputs between 1000 (k), 1024 (K), 1000000 (m), or 1048576 (M) bytes"),
-            // arg!(-t --timestamp "Append timestamp to each line"),
+            arg!(-t --timestamp "Append timestamp to each line"),
             arg!(-w --wide "Wide output mode"),
             arg!(-y --"no-first" "Omits first report with statistics since system boot"),
         ])

tests/by-util/test_vmstat.rs

@@ -69,3 +69,15 @@ fn test_active() {
         .unwrap()
         .contains("active"));
 }
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_timestamp() {
+    let result = new_ucmd!().arg("-t").succeeds();
+    assert!(result
+        .stdout_str()
+        .lines()
+        .next()
+        .unwrap()
+        .contains("timestamp"));
+}