On Wed, Mar 31, 2010 at 3:55 AM, Murali K. Vemuri <[email protected]> wrote:
> Hi ,
>
> I use busybox version 1.16.1.
> I have two processes that have to be running all the time, but with some
> differences in behavior.
>
> process 1: This process must be up and running all the time, but need
> not be re-run every now and then. All I need is to ensure this process
> exits, its automatically re-run.
>
> process 2: this process has a life span of about 20 seconds. So, I need
> to make sure every 20 sec, this is run. This process exits
> automatically.
Looks like you want to run these using runsv (possibly with runsvdir).
See examples/var_service/*.
Basically, "runsvdir examples/var_service" would start
"runsv examples/var_service/SUBDIR" for every SUBDIR,
each of those will run examples/var_service/SUBDIR/run
and when it exits, rerun it again. "sv" tool controls these
services. For example, sv d DIR stops service in DIR.
Let me know if documentation on them is missing or inadequate.
> In the second case, I use "watch -t -n 25 process2" and that serves my
> purpose.
Wrong tool for the job.
> BTW, I made a small change in watch.c when -t option is used.
>
> orig code:
>
> if (!(opt & 0x2)) { // no -t
> const unsigned time_len = sizeof("1234-67-90 23:56:89");
> time_t t;
>
> // STDERR_FILENO is procps3 compat:
> // "watch ls 2>/dev/null" does not detect tty size
> get_terminal_width_height(STDERR_FILENO, &new_width, NULL);
> if (new_width != width) {
> width = new_width;
> free(header);
> header = xasprintf("Every %us: %-*s", period,
> (int)width, cmd);
> }
> time(&t);
> if (time_len < width)
> strftime(header + width - time_len, time_len,
> "%Y-%m-%d %H:%M:%S", localtime(&t));
>
> // compat: empty line between header and cmd output
> printf("%s\n\n", header);
> }
> fflush_all();
>
> my change:
>
> move the fflush_all() into the if condition like this:
>
> if (!(opt & 0x2)) { // no -t
> const unsigned time_len = sizeof("1234-67-90 23:56:89");
> time_t t;
> fflush_all();
> ....
> .....
> }
Why is this needed/useful?
> The user specifies the -t option only if he wants to do the "watch"
> silently. if the screen refreshes every often, does not look nice.
Why do you think -t means "watch silently"?
--
vda
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