vmstat: implement --forks

src/uu/vmstat/src/vmstat.rs

@@ -26,6 +26,9 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let matches = uu_app().try_get_matches_from(args)?;
     #[cfg(target_os = "linux")]
     {
+        if matches.get_flag("forks") {
+            return print_forks();
+        }
         if matches.get_flag("stats") {
             return print_stats();
         }
@@ -83,6 +86,16 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     Ok(())
 }
 
+#[cfg(target_os = "linux")]
+fn print_forks() -> UResult<()> {
+    let data = get_stats();
+
+    let fork_data = data.last().unwrap();
+    println!("{:>13} {}", fork_data.1, fork_data.0);
+
+    Ok(())
+}
+
 #[cfg(target_os = "linux")]
 fn print_stats() -> UResult<()> {
     let data = get_stats();
@@ -177,10 +190,13 @@ pub fn uu_app() -> Command {
                 .required(false)
                 .value_parser(value_parser!(u64)),
             arg!(-a --active "Display active and inactive memory"),
-            // arg!(-f --forks "switch displays the number of forks since boot"),
-            arg!(-m --slabs "Display slabinfo"),
+            arg!(-f --forks "switch displays the number of forks since boot")
+                .conflicts_with_all(["slabs", "stats", /*"disk", "disk-sum", "partition"*/]),
+            arg!(-m --slabs "Display slabinfo")
+                .conflicts_with_all(["forks", "stats", /*"disk", "disk-sum", "partition"*/]),
             arg!(-n --"one-header" "Display the header only once rather than periodically"),
-            arg!(-s --stats "Displays a table of various event counters and memory statistics"),
+            arg!(-s --stats "Displays a table of various event counters and memory statistics")
+                .conflicts_with_all(["forks", "slabs", /*"disk", "disk-sum", "partition"*/]),
             // arg!(-d --disk "Report disk statistics"),
             // arg!(-D --"disk-sum" "Report some summary statistics about disk activity"),
             // arg!(-p --partition <device> "Detailed statistics about partition"),

tests/by-util/test_vmstat.rs

@@ -19,6 +19,11 @@ fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails().code_is(1);
 }
 
+#[test]
+fn test_conflict_arg() {
+    new_ucmd!().args(&["-s", "-m"]).fails().code_is(1);
+}
+
 #[test]
 fn test_invalid_number() {
     new_ucmd!().arg("-1").fails().code_is(1);