procps/watch.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini watch implementation for busybox
   4  *
   5  * Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
   6  * Copyrigjt (C) Mar 16, 2003 Manuel Novoa III   (mjn3@codepoet.org)
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   9  */
  10
  11 /* BB_AUDIT SUSv3 N/A */
  12 /* BB_AUDIT GNU defects -- only option -n is supported. */
  13
  14 #include "libbb.h"
  15
  16 // procps 2.0.18:
  17 // watch [-d] [-n seconds]
  18 //   [--differences[=cumulative]] [--interval=seconds] command
  19 //
  20 // procps-3.2.3:
  21 // watch [-dt] [-n seconds]
  22 //   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
  23 //
  24 // (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
  25
  26 int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  27 int watch_main(int argc, char **argv)
  28 {
  29         unsigned opt;
  30         unsigned period = 2;
  31         unsigned cmdlen;
  32         char *header = NULL;
  33         char *cmd;
  34         char *tmp;
  35         char **p;
  36
  37         opt_complementary = "-1"; // at least one param please
  38         opt = getopt32(argv, "+dtn:", &tmp);
  39         //if (opt & 0x1) // -d (ignore)
  40         //if (opt & 0x2) // -t
  41         if (opt & 0x4) period = xatou(tmp);
  42         argv += optind;
  43
  44         p = argv;
  45         cmdlen = 1; // 1 for terminal NUL
  46         while (*p)
  47                 cmdlen += strlen(*p++) + 1;
  48         tmp = cmd = xmalloc(cmdlen);
  49         while (*argv) {
  50                 tmp += sprintf(tmp, " %s", *argv);
  51                 argv++;
  52         }
  53         cmd++; // skip initial space
  54
  55         while (1) {
  56                 printf("\033[H\033[J");
  57                 if (!(opt & 0x2)) { // no -t
  58                         int width, len;
  59                         char *thyme;
  60                         time_t t;
  61
  62                         get_terminal_width_height(STDIN_FILENO, &width, 0);
  63                         header = xrealloc(header, width--);
  64                         // '%-*s' pads header with spaces to the full width
  65                         snprintf(header, width, "Every %ds: %-*s", period, width, cmd);
  66                         time(&t);
  67                         thyme = ctime(&t);
  68                         len = strlen(thyme);
  69                         if (len < width)
  70                                 strcpy(header + width - len, thyme);
  71                         puts(header);
  72                 }
  73                 fflush(stdout);
  74                 // TODO: 'real' watch pipes cmd's output to itself
  75                 // and does not allow it to overflow the screen
  76                 // (taking into account linewrap!)
  77                 system(cmd);
  78                 sleep(period);
  79         }
  80         return 0; // gcc thinks we can reach this :)
  81 }