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New option: --pid=PID.

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(pid): New global.
(long_options): Add `pid'.
(usage): Describe it.
(tail_forever): Implement it.
(parse_options): Handle the new option and required arg.
Suggestion and pseudo-code from Karl Heuer.
This commit is contained in:
Jim Meyering
1999-07-30 20:42:39 +00:00
parent d883ecee8a
commit 4d70e59a85
1 changed files with 29 additions and 1 deletions
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30
src/tail.c
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@@ -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;