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watch: add -exec and -beep flags and has better quoting

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Additionally add -errexit flag (#183346).

A patch from Debian.

Bug-Debian: http://bugs.debian.org/410967
Bug-Debian: http://bugs.debian.org/183346
Reviewed-by: Craig Small <csmall@debian.org>
Backported-by: Sami Kerola <kerolasa@iki.fi>
This commit is contained in:
Mordechai T. Abzug 2009-11-24 11:00:43 +11:00 committed by Craig Small
parent 99bebff06a
commit db552d38bc
2 changed files with 116 additions and 10 deletions
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33
watch.1
View File

@ -4,10 +4,13 @@ watch \- execute a program periodically, showing output fullscreen
.SH SYNOPSIS
.na
.B watch
.RB [ \-dhvt ]
.RB [ \-bdehvtx ]
.RB [ \-n
.IR seconds ]
.RB [ \-\-beep ]
.RB [ \-\-differences[=\fIcumulative\fP]]
.RB [ \-\-errexit ]
.RB [ \-\-exec ]
.RB [ \-\-help ]
.RB [ \-\-interval=\fIseconds\fP]
.RB [ \-\-no\-title ]
@ -17,7 +20,8 @@ watch \- execute a program periodically, showing output fullscreen
.B watch
runs
.I command
repeatedly, displaying its output (the first screenfull). This allows you to
repeatedly, displaying its output and errors (the first screenfull). This
allows you to
watch the program output change over time. By default, the program is run
every 2 seconds; use
.B \-n
@ -37,15 +41,33 @@ positions that have ever changed. The
or
.B \-\-no\-title
option turns off the header showing the interval, command, and current
time at the top of the display, as well as the following blank line.
time at the top of the display, as well as the following blank line. The
.I \-b
or
.I \-\-beep
option causes the command to beep if it has a non-zero exit.
.PP
.B watch
will run until interrupted.
will normally run until interrupted. If you want
.B watch
to exit on an error from the program running use the
.I \-e
or
.I \-\-errexit
options, which will cause
.B watch
to exit if the return value from the program is non-zero.
.SH NOTE
Note that
.I command
is given to "sh \-c"
which means that you may need to use extra quoting to get the desired effect.
You can disable this with the
.I -x
or
.I --exec
option, which passes the command to exec(2) instead.
.PP
Note that POSIX option processing is used (i.e., option processing stops at
the first non\-option argument). This means that flags after
@ -93,4 +115,5 @@ The original
.B watch
was written by Tony Rems <rembo@unisoft.com> in 1991, with mods and
corrections by Francois Pinard. It was reworked and new features added by
Mike Coleman <mkc@acm.org> in 1999.
Mike Coleman <mkc@acm.org> in 1999. The beep, exec, and error handling
features were added by Morty Abzug <morty@frakir.org> in 2008.

93
watch.c
View File

@ -8,6 +8,7 @@
* Mike Coleman <mkc@acm.org>.
*
* Changes by Albert Cahalan, 2002-2003.
* stderr handling, exec, and beep option added by Morty Abzug, 2008
*/
#include <ctype.h>
@ -34,13 +35,16 @@ static struct option longopts[] = {
{"differences", optional_argument, 0, 'd'},
{"help", no_argument, 0, 'h'},
{"interval", required_argument, 0, 'n'},
{"beep", no_argument, 0, 'b'},
{"errexit", no_argument, 0, 'e'},
{"exec", no_argument, 0, 'x'},
{"no-title", no_argument, 0, 't'},
{"version", no_argument, 0, 'v'},
{0, 0, 0, 0}
};
static char usage[] =
"Usage: %s [-dhntv] [--differences[=cumulative]] [--help] [--interval=<n>] [--no-title] [--version] <command>\n";
"Usage: %s [-bdhntvx] [--beep] [--differences[=cumulative]] [--exec] [--help] [--interval=<n>] [--no-title] [--version] <command>\n";
static char *progname;
@ -139,28 +143,44 @@ main(int argc, char *argv[])
int optc;
int option_differences = 0,
option_differences_cumulative = 0,
option_exec = 0,
option_beep = 0,
option_errexit = 0,
option_help = 0, option_version = 0;
double interval = 2;
char *command;
char **command_argv;
int command_length = 0; /* not including final \0 */
int pipefd[2];
int status;
pid_t child;
setlocale(LC_ALL, "");
progname = argv[0];
while ((optc = getopt_long(argc, argv, "+d::hn:vt", longopts, (int *) 0))
while ((optc = getopt_long(argc, argv, "+bed::hn:vtx", longopts, (int *) 0))
!= EOF) {
switch (optc) {
case 'b':
option_beep = 1;
break;
case 'd':
option_differences = 1;
if (optarg)
option_differences_cumulative = 1;
break;
case 'e':
option_errexit = 1;
break;
case 'h':
option_help = 1;
break;
case 't':
show_title = 0;
break;
case 'x':
option_exec = 1;
break;
case 'n':
{
char *str;
@ -190,18 +210,23 @@ main(int argc, char *argv[])
if (option_help) {
fprintf(stderr, usage, progname);
fputs(" -b, --beep\t\t\t\tbeep if the command has a non-zero exit\n", stderr);
fputs(" -d, --differences[=cumulative]\thighlight changes between updates\n", stderr);
fputs("\t\t(cumulative means highlighting is cumulative)\n", stderr);
fputs(" -e, --errexit\t\t\t\texit watch if the command has a non-zero exit\n", stderr);
fputs(" -h, --help\t\t\t\tprint a summary of the options\n", stderr);
fputs(" -n, --interval=<seconds>\t\tseconds to wait between updates\n", stderr);
fputs(" -v, --version\t\t\t\tprint the version number\n", stderr);
fputs(" -t, --no-title\t\t\tturns off showing the header\n", stderr);
fputs(" -x, --exec\t\t\t\tpass command to exec instead of sh\n", stderr);
exit(0);
}
if (optind >= argc)
do_usage();
command_argv=&(argv[optind]); /* save for later */
command = strdup(argv[optind++]);
command_length = strlen(command);
for (; optind < argc; optind++) {
@ -260,11 +285,57 @@ main(int argc, char *argv[])
free(header);
}
if (!(p = popen(command, "r"))) {
perror("popen");
/* allocate pipes */
if (pipe(pipefd)<0) {
perror("pipe");
do_exit(7);
}
/* flush stdout and stderr, since we're about to do fd stuff */
fflush(stdout);
fflush(stderr);
/* fork to prepare to run command */
child=fork();
if (child<0) { /* fork error */
perror("fork");
do_exit(2);
} else if (child==0) { /* in child */
close (pipefd[0]); /* child doesn't need read side of pipe */
close (1); /* prepare to replace stdout with pipe */
if (dup2 (pipefd[1], 1)<0) { /* replace stdout with write side of pipe */
perror("dup2");
exit(3);
}
dup2(1, 2); /* stderr should default to stdout */
if (option_exec) { /* pass command to exec instead of system */
if (execvp(command_argv[0], command_argv)==-1) {
perror("exec");
exit(4);
}
} else {
status=system(command); /* watch manpage promises sh quoting */
/* propagate command exit status as child exit status */
if (!WIFEXITED(status)) { /* child exits nonzero if command does */
exit(1);
} else {
exit(WEXITSTATUS(status));
}
}
}
/* otherwise, we're in parent */
close(pipefd[1]); /* close write side of pipe */
if ((p=fdopen(pipefd[0], "r"))==NULL) {
perror("fdopen");
do_exit(5);
}
for (y = show_title; y < height; y++) {
int eolseen = 0, tabpending = 0;
for (x = 0; x < width; x++) {
@ -312,7 +383,19 @@ main(int argc, char *argv[])
oldeolseen = eolseen;
}
pclose(p);
fclose(p);
/* harvest child process and get status, propagated from command */
if (waitpid(child, &status, 0)<0) {
perror("waitpid");
do_exit(8);
};
/* if child process exited in error, beep if option_beep is set */
if ((!WIFEXITED(status) || WEXITSTATUS(status))) {
if (option_beep) beep();
if (option_errexit) do_exit(8);
}
first_screen = 0;
refresh();