watch: add -r to not rexec on terminal resize

If you have the watched program doing some other thing every time its
run and you resize the window, you might get unexpected results. The
-r option lets you run only when the interval has expired.

References:
 procps-ng/procps!125
 procps-ng/procps#190
This commit is contained in:
Craig Small 2023-01-17 20:45:48 +11:00
parent 5f4074a250
commit b2bfd76b06
3 changed files with 56 additions and 35 deletions

1
NEWS
View File

@ -9,6 +9,7 @@ procps-ng-NEXT
* vmstat: Referesh memory statistics Debian #1027963
* w: Add --pids option merge #159
* watch: Pass through beep issue #104
* watch: -r option to not re-exec on SIGWINCH merge #125
procps-ng-4.0.2
---------------

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@ -1,4 +1,4 @@
.TH WATCH 1 "2023-01-16" "procps-ng" "User Commands"
.TH WATCH 1 "2023-01-17" "procps-ng" "User Commands"
.SH NAME
watch \- execute a program periodically, showing output fullscreen
.SH SYNOPSIS
@ -13,12 +13,26 @@ allows you to watch the program output change over time. By default,
\fIcommand\fR is run every 2 seconds and \fBwatch\fR will run until interrupted.
.SH OPTIONS
.TP
\fB\-b\fR, \fB\-\-beep\fR
Beep if command has a non-zero exit.
.TP
\fB\-c\fR, \fB\-\-color\fR
Interpret ANSI color and style sequences.
.TP
\fB\-d\fR, \fB\-\-differences\fR[=\fIpermanent\fR]
Highlight the differences between successive updates. If the optional
\fIpermanent\fR argument is specified then
.B watch
will show all changes since the first iteration.
.TP
\fB\-e\fR, \fB\-\-errexit\fR
Freeze updates on command error, and exit after a key press.
.TP
\fB\-g\fR, \fB\-\-chgexit\fR
Exit when the output of
.I command
changes.
.TP
\fB\-n\fR, \fB\-\-interval\fR \fIseconds\fR
Specify update interval. The command will not allow quicker than 0.1 second
interval, in which the smaller values are converted. Both '.' and ',' work
@ -38,28 +52,21 @@ Try it with
(if present) and notice how the fractional seconds stays (nearly) the same, as opposed to
normal mode where they continuously increase.
.TP
\fB\-t\fR, \fB\-\-no\-title\fR
Turn off the header showing the interval, command, and current time at the
top of the display, as well as the following blank line.
.TP
\fB\-b\fR, \fB\-\-beep\fR
Beep if command has a non-zero exit.
.TP
\fB\-e\fR, \fB\-\-errexit\fR
Freeze updates on command error, and exit after a key press.
.TP
\fB\-g\fR, \fB\-\-chgexit\fR
Exit when the output of
.I command
changes.
.TP
\fB\-q\fR, \fB\-\-equexit\fR <cycles>
Exit when output of
.I command
does not change for the given number of cycles.
.TP
\fB\-c\fR, \fB\-\-color\fR
Interpret ANSI color and style sequences.
\fB\-r\fR, \fB\-\-no-rerun\fR
Do not run the program on terminal resize, the output of the program will re-appear at the next
regular run time.
.TP
\fB\-t\fR, \fB\-\-no\-title\fR
Turn off the header showing the interval, command, and current time at the
top of the display, as well as the following blank line.
.TP
\fB\-w\fR, \fB\-\-no\-wrap\fR
Turn off line wrapping. Long lines will be truncated instead of wrapped to the next line.
.TP
\fB\-x\fR, \fB\-\-exec\fR
Pass
@ -70,9 +77,6 @@ instead of
.B sh \-c
which reduces the need to use extra quoting to get the desired effect.
.TP
\fB\-w\fR, \fB\-\-no\-wrap\fR
Turn off line wrapping. Long lines will be truncated instead of wrapped to the next line.
.TP
\fB\-h\fR, \fB\-\-help\fR
Display help text and exit.
.TP
@ -134,7 +138,9 @@ itself.
Upon terminal resize, the screen will not be correctly repainted until the
next scheduled update. All
.B \-\-differences
highlighting is lost on that update as well.
highlighting is lost on that update as well. When using the
.B \-\-no\-rerun
option, no output of will be visible.
Non-printing characters are stripped from program output. Use \fBcat -v\fR as
part of the command pipeline if you want to see them.

View File

@ -72,6 +72,7 @@ static int flags;
#define WATCH_ERREXIT (1 << 6)
#define WATCH_CHGEXIT (1 << 7)
#define WATCH_EQUEXIT (1 << 8)
#define WATCH_NORERUN (1 << 9)
static int curses_started = 0;
static long height = 24, width = 80;
@ -101,6 +102,7 @@ static void __attribute__ ((__noreturn__))
" exit when output from command does not change\n"), out);
fputs(_(" -n, --interval <secs> seconds to wait between updates\n"), out);
fputs(_(" -p, --precise attempt run command in precise intervals\n"), out);
fputs(_(" -r, --no-rerun do not rerun program on window resize\n"), out);
fputs(_(" -t, --no-title turn off header\n"), out);
fputs(_(" -w, --no-wrap turn off line wrapping\n"), out);
fputs(_(" -x, --exec pass command to exec instead of \"sh -c\"\n"), out);
@ -814,6 +816,7 @@ int main(int argc, char *argv[])
char *command;
char **command_argv;
int command_length = 0; /* not including final \0 */
watch_usec_t last_run = 0;
watch_usec_t next_loop; /* next loop time in us, used for precise time
* keeping only */
#ifdef WITH_WATCH8BIT
@ -832,6 +835,7 @@ int main(int argc, char *argv[])
{"equexit", required_argument, 0, 'q'},
{"exec", no_argument, 0, 'x'},
{"precise", no_argument, 0, 'p'},
{"no-rerun", no_argument, 0, 'r'},
{"no-title", no_argument, 0, 't'},
{"no-wrap", no_argument, 0, 'w'},
{"version", no_argument, 0, 'v'},
@ -851,7 +855,7 @@ int main(int argc, char *argv[])
interval = strtod_nol_or_err(interval_string, _("Could not parse interval from WATCH_INTERVAL"));
while ((optc =
getopt_long(argc, argv, "+bced::ghq:n:pvtwx", longopts, (int *)0))
getopt_long(argc, argv, "+bced::ghq:n:prtwvx", longopts, (int *)0))
!= EOF) {
switch (optc) {
case 'b':
@ -875,6 +879,9 @@ int main(int argc, char *argv[])
flags |= WATCH_EQUEXIT;
max_cycles = strtod_nol_or_err(optarg, _("failed to parse argument"));
break;
case 'r':
flags |= WATCH_NORERUN;
break;
case 't':
show_title = 0;
break;
@ -990,18 +997,25 @@ int main(int argc, char *argv[])
output_header(command, interval);
#endif /* WITH_WATCH8BIT */
int exit = run_command(command, command_argv);
if (flags & WATCH_EQUEXIT) {
if (cycle_count == max_cycles && exit) {
break;
} else if (exit) {
cycle_count++;
} else {
cycle_count = 0;
}
} else if (exit) {
break;
}
if (!(flags & WATCH_NORERUN) ||
get_time_usec() - last_run > interval * USECS_PER_SEC) {
last_run = get_time_usec();
int exit = run_command(command, command_argv);
if (flags & WATCH_EQUEXIT) {
if (cycle_count == max_cycles && exit) {
break;
} else if (exit) {
cycle_count++;
} else {
cycle_count = 0;
}
} else if (exit) {
break;
}
} else {
refresh();
}
if (precise_timekeeping) {
watch_usec_t cur_time = get_time_usec();