vmstat: Provides option to omit first report

The first report from vmstat provides statistics since system boot. This is
often thrown out. Thus, this provides a command line option to omit it. The
program still provides <count> reports.

Signed-off-by: Sanskriti Sharma <sansharm@redhat.com>

vmstat.c

@@ -80,6 +80,9 @@ static int a_option;
 /* "-w" means "wide output" */
 static int w_option;
 
+/* "-y" means "skip first output" */
+static int y_option;
+
 /* "-t" means "show timestamp" */
 static int t_option;
 
@@ -232,6 +235,7 @@ static void __attribute__ ((__noreturn__))
     fputs(_(" -S, --unit <char>      define display unit\n"), out);
     fputs(_(" -w, --wide             wide output\n"), out);
     fputs(_(" -t, --timestamp        show timestamp\n"), out);
+    fputs(_(" -y, --no-first         skips first line of output\n"), out);
     fputs(USAGE_SEPARATOR, out);
     fputs(USAGE_HELP, out);
     fputs(USAGE_VERSION, out);
@@ -378,6 +382,15 @@ static void new_format(void)
     if (procps_meminfo_new(&mem_info) < 0)
         xerrx(EXIT_FAILURE, _("Unable to create meminfo structure"));
 
+    pgpgin[tog] = VMSTAT_GET(vm_info, VMSTAT_PGPGIN, ul_int);
+    pgpgout[tog] = VMSTAT_GET(vm_info, VMSTAT_PGPGOUT, ul_int);
+    pswpin[tog] = VMSTAT_GET(vm_info, VMSTAT_PSWPIN, ul_int);
+    pswpout[tog] = VMSTAT_GET(vm_info, VMSTAT_PSWPOUT, ul_int);
+
+    if (!(mem_stack = procps_meminfo_select(mem_info, Mem_items, MAX_mem)))
+        xerrx(EXIT_FAILURE, _("Unable to select memory information"));
+
+    if (y_option == 0) {
         if (t_option) {
             (void) time( &the_time );
             tm_ptr = localtime( &the_time );
@@ -397,14 +410,6 @@ static void new_format(void)
         cpu_sto = TICv(stat_STO);
         cpu_gue = TICv(stat_GST) + TICv(stat_GNI);
 
-    pgpgin[tog] = VMSTAT_GET(vm_info, VMSTAT_PGPGIN, ul_int);
-    pgpgout[tog] = VMSTAT_GET(vm_info, VMSTAT_PGPGOUT, ul_int);
-    pswpin[tog] = VMSTAT_GET(vm_info, VMSTAT_PSWPIN, ul_int);
-    pswpout[tog] = VMSTAT_GET(vm_info, VMSTAT_PSWPOUT, ul_int);
-
-    if (!(mem_stack = procps_meminfo_select(mem_info, Mem_items, MAX_mem)))
-        xerrx(EXIT_FAILURE, _("Unable to select memory information"));
-
         Div = cpu_use + cpu_sys + cpu_idl + cpu_iow + cpu_sto;
         if (!Div) {
             Div = 1;
@@ -439,6 +444,8 @@ static void new_format(void)
         }
 
         printf("\n");
+    } else
+        num_updates++;
 
     /* main loop */
     for (i = 1; infinite_updates || i < num_updates; i++) {
@@ -944,6 +951,7 @@ int main(int argc, char *argv[])
         {"timestamp", no_argument, NULL, 't'},
         {"help", no_argument, NULL, 'h'},
         {"version", no_argument, NULL, 'V'},
+        {"no-first", no_argument, NULL, 'y'},
         {NULL, 0, NULL, 0}
     };
 
@@ -956,7 +964,7 @@ int main(int argc, char *argv[])
     atexit(close_stdout);
 
     while ((c =
-        getopt_long(argc, argv, "afmnsdDp:S:wthV", longopts, NULL)) != -1)
+        getopt_long(argc, argv, "afmnsdDp:S:wthVy", longopts, NULL)) != -1)
         switch (c) {
         case 'V':
             printf(PROCPS_NG_VERSION);
@@ -1023,6 +1031,10 @@ int main(int argc, char *argv[])
         case 't':
             t_option = 1;
             break;
+        case 'y':
+            /* Don't display stats since system restart */
+            y_option = 1;
+            break;
         default:
             /* no other aguments defined yet. */
             usage(stderr);