diff options
| -rw-r--r-- | src/tail.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/src/tail.c b/src/tail.c index 771920a4c..60b7560a7 100644 --- a/src/tail.c +++ b/src/tail.c @@ -172,6 +172,10 @@ char *program_name; /* FIXME: allow fractional seconds */ static unsigned int sleep_interval = 1; +/* The process ID of the process (presumably on the current host) + that is writing to all followed files. */ +static pid_t pid; + /* Nonzero if we have ever read standard input. */ static int have_read_stdin; @@ -185,6 +189,7 @@ static struct option const long_options[] = {"lines", required_argument, NULL, 'n'}, {"max-unchanged-stats", required_argument, NULL, CHAR_MAX + 2}, {"max-consecutive-size-changes", required_argument, NULL, CHAR_MAX + 3}, + {"pid", required_argument, NULL, CHAR_MAX + 4}, {"quiet", no_argument, NULL, 'q'}, {"retry", no_argument, NULL, CHAR_MAX + 1}, {"silent", no_argument, NULL, 'q'}, @@ -224,6 +229,7 @@ With no FILE, or when FILE is -, read standard input.\n\ (the default is %d)\n\ --max-consecutive-size-changes=N see the texinfo documentation\n\ (the default is %d)\n\ + --pid=PID with -f, terminate after process ID, PID dies\n\ -q, --quiet, --silent never output headers giving file names\n\ -s, --sleep-interval=S with -f, sleep S seconds between iterations\n\ -v, --verbose always output headers giving file names\n\ @@ -818,6 +824,7 @@ static void tail_forever (struct File_spec *f, int nfiles) { int last; + int writer_is_dead = 0; last = nfiles - 1; @@ -907,7 +914,15 @@ tail_forever (struct File_spec *f, int nfiles) /* If none of the files changed size, sleep. */ if (!any_changed) - sleep (sleep_interval); + { + if (writer_is_dead) + break; + sleep (sleep_interval); + + /* Once the writer is dead, read the files once more to + avoid a race condition. */ + writer_is_dead = (kill (pid, 0) != 0); + } } } @@ -1364,6 +1379,19 @@ parse_options (int argc, char **argv, } break; + case CHAR_MAX + 4: + { + strtol_error s_err; + unsigned long int tmp_ulong; + s_err = xstrtoul (optarg, NULL, 10, &tmp_ulong, ""); + if (s_err != LONGINT_OK || tmp_ulong > PID_T_MAX) + { + error (EXIT_FAILURE, 0, _("%s: invalid PID"), optarg); + } + pid = tmp_ulong; + } + break; + case 'q': *header_mode = never; break; |