journalctl: only output 10 most recent lines in --follow mode

diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index 0e1fb66de6da8a5aa49af56369dbb4d6cf6d3cc7..e888990f23ece613d332fe3e69d49bdba73f7ade 100644 (file)
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -38,11 +38,11 @@
 #include "logs-show.h"
 
 static output_mode arg_output = OUTPUT_SHORT;
-
 static bool arg_follow = false;
 static bool arg_show_all = false;
 static bool arg_no_pager = false;
 static int arg_lines = -1;
+static bool arg_no_tail = false;
 
 static int help(void) {
 
@@ -54,6 +54,7 @@ static int help(void) {
                "  -a --all            Show all properties, including long and unprintable\n"
                "  -f --follow         Follow journal\n"
                "  -n --lines=INTEGER  Lines to show\n"
+               "     --no-tail        Show all lines, even in follow mode\n"
                "  -o --output=STRING  Change output mode (short, verbose, export, json)\n",
                program_invocation_short_name);
 
@@ -64,7 +65,8 @@ static int parse_argv(int argc, char *argv[]) {
 
         enum {
                 ARG_VERSION = 0x100,
-                ARG_NO_PAGER
+                ARG_NO_PAGER,
+                ARG_NO_TAIL
         };
 
         static const struct option options[] = {
@@ -75,6 +77,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "output",    required_argument, NULL, 'o'           },
                 { "all",       no_argument,       NULL, 'a'           },
                 { "lines",     required_argument, NULL, 'n'           },
+                { "no-tail",   no_argument,       NULL, ARG_NO_TAIL   },
                 { NULL,        0,                 NULL, 0             }
         };
 
@@ -126,12 +129,16 @@ static int parse_argv(int argc, char *argv[]) {
 
                 case 'n':
                         r = safe_atoi(optarg, &arg_lines);
-                        if (r < 0) {
+                        if (r < 0 || arg_lines < 0) {
                                 log_error("Failed to parse lines '%s'", optarg);
                                 return -EINVAL;
                         }
                         break;
 
+                case ARG_NO_TAIL:
+                        arg_no_tail = true;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -141,6 +148,9 @@ static int parse_argv(int argc, char *argv[]) {
                 }
         }
 
+        if (arg_follow && !arg_no_tail)
+                arg_lines = 10;
+
         return 1;
 }