busybox/coreutils/watch.c

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/* vi: set sw=4 ts=4: */
/*
* Mini watch implementation for busybox
*
* Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
* Copyrigjt (C) Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
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*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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/* BB_AUDIT SUSv3 N/A */
/* BB_AUDIT GNU defects -- only option -n is supported. */
#include "libbb.h"
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// procps 2.0.18:
// watch [-d] [-n seconds]
// [--differences[=cumulative]] [--interval=seconds] command
//
// procps-3.2.3:
// watch [-dt] [-n seconds]
// [--differences[=cumulative]] [--interval=seconds] [--no-title] command
//
// (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
int watch_main(int argc, char **argv);
int watch_main(int argc, char **argv)
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{
unsigned opt;
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unsigned period = 2;
unsigned cmdlen = 1; // 1 for terminal NUL
char *header = NULL;
char *cmd;
char *tmp;
char **p;
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opt_complementary = "-1"; // at least one param please
opt = getopt32(argc, argv, "+dtn:", &tmp);
//if (opt & 0x1) // -d (ignore)
//if (opt & 0x2) // -t
if (opt & 0x4) period = xatou(tmp);
argv += optind;
p = argv;
while (*p)
cmdlen += strlen(*p++) + 1;
tmp = cmd = xmalloc(cmdlen);
while (*argv) {
tmp += sprintf(tmp, " %s", *argv);
argv++;
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}
cmd++; // skip initial space
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while (1) {
printf("\033[H\033[J");
if (!(opt & 0x2)) { // no -t
int width, len;
char *thyme;
time_t t;
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get_terminal_width_height(STDOUT_FILENO, &width, 0);
header = xrealloc(header, width--);
// '%-*s' pads header with spaces to the full width
snprintf(header, width, "Every %ds: %-*s", period, width, cmd);
time(&t);
thyme = ctime(&t);
len = strlen(thyme);
if (len < width)
strcpy(header + width - len, thyme);
puts(header);
}
fflush(stdout);
// TODO: 'real' watch pipes cmd's output to itself
// and does not allow it to overflow the screen
// (taking into account linewrap!)
system(cmd);
sleep(period);
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}
return 0; // gcc thinks we can reach this :)
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}