LXR busybox/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 source tree.
   9 */
  10
  11/* BB_AUDIT SUSv3 N/A */
  12/* BB_AUDIT GNU defects -- only option -n is supported. */
  13
  14//usage:#define watch_trivial_usage
  15//usage:       "[-n SEC] [-t] PROG ARGS"
  16//usage:#define watch_full_usage "\n\n"
  17//usage:       "Run PROG periodically\n"
  18//usage:     "\n        -n      Loop period in seconds (default 2)"
  19//usage:     "\n        -t      Don't print header"
  20//usage:
  21//usage:#define watch_example_usage
  22//usage:       "$ watch date\n"
  23//usage:       "Mon Dec 17 10:31:40 GMT 2000\n"
  24//usage:       "Mon Dec 17 10:31:42 GMT 2000\n"
  25//usage:       "Mon Dec 17 10:31:44 GMT 2000"
  26
  27#include "libbb.h"
  28
  29// procps 2.0.18:
  30// watch [-d] [-n seconds]
  31//   [--differences[=cumulative]] [--interval=seconds] command
  32//
  33// procps-3.2.3:
  34// watch [-dt] [-n seconds]
  35//   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
  36//
  37// (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
  38
  39int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  40int watch_main(int argc UNUSED_PARAM, char **argv)
  41{
  42        unsigned opt;
  43        unsigned period = 2;
  44        unsigned width, new_width;
  45        char *header;
  46        char *cmd;
  47
  48#if 0 // maybe ENABLE_DESKTOP?
  49        // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
  50        close(STDIN_FILENO);
  51        xopen("/dev/null", O_RDONLY);
  52#endif
  53
  54        opt_complementary = "-1:n+"; // at least one param; -n NUM
  55        // "+": stop at first non-option (procps 3.x only)
  56        opt = getopt32(argv, "+dtn:", &period);
  57        argv += optind;
  58
  59        // watch from both procps 2.x and 3.x does concatenation. Example:
  60        // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
  61        cmd = *argv;
  62        while (*++argv)
  63                cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
  64
  65        width = (unsigned)-1; // make sure first time new_width != width
  66        header = NULL;
  67        while (1) {
  68                /* home; clear to the end of screen */
  69                printf("\033[H""\033[J");
  70                if (!(opt & 0x2)) { // no -t
  71                        const unsigned time_len = sizeof("1234-67-90 23:56:89");
  72                        time_t t;
  73
  74                        // STDERR_FILENO is procps3 compat:
  75                        // "watch ls 2>/dev/null" does not detect tty size
  76                        get_terminal_width_height(STDERR_FILENO, &new_width, NULL);
  77                        if (new_width != width) {
  78                                width = new_width;
  79                                free(header);
  80                                header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
  81                        }
  82                        time(&t);
  83                        if (time_len < width)
  84                                strftime(header + width - time_len, time_len,
  85                                        "%Y-%m-%d %H:%M:%S", localtime(&t));
  86
  87                        // compat: empty line between header and cmd output
  88                        printf("%s\n\n", header);
  89                }
  90                fflush_all();
  91                // TODO: 'real' watch pipes cmd's output to itself
  92                // and does not allow it to overflow the screen
  93                // (taking into account linewrap!)
  94                system(cmd);
  95                sleep(period);
  96        }
  97        return 0; // gcc thinks we can reach this :)
  98}
  99