source: MondoRescue/branches/3.3/mindi-busybox/procps/watch.c@ 3621

/* 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)
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

/* BB_AUDIT SUSv3 N/A */
/* BB_AUDIT GNU defects -- only option -n is supported. */

//usage:#define watch_trivial_usage
//usage:       "[-n SEC] [-t] PROG ARGS"
//usage:#define watch_full_usage "\n\n"
//usage:       "Run PROG periodically\n"
//usage:     "\n    -n  Loop period in seconds (default 2)"
//usage:     "\n    -t  Don't print header"
//usage:
//usage:#define watch_example_usage
//usage:       "$ watch date\n"
//usage:       "Mon Dec 17 10:31:40 GMT 2000\n"
//usage:       "Mon Dec 17 10:31:42 GMT 2000\n"
//usage:       "Mon Dec 17 10:31:44 GMT 2000"

#include "libbb.h"

// 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) MAIN_EXTERNALLY_VISIBLE;
int watch_main(int argc UNUSED_PARAM, char **argv)
{
    unsigned opt;
    unsigned period = 2;
    unsigned width, new_width;
    char *header;
    char *cmd;

#if 0 // maybe ENABLE_DESKTOP?
    // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
    close(STDIN_FILENO);
    xopen("/dev/null", O_RDONLY);
#endif

    opt_complementary = "-1:n+"; // at least one param; -n NUM
    // "+": stop at first non-option (procps 3.x only)
    opt = getopt32(argv, "+dtn:", &period);
    argv += optind;

    // watch from both procps 2.x and 3.x does concatenation. Example:
    // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
    cmd = *argv;
    while (*++argv)
        cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd

    width = (unsigned)-1; // make sure first time new_width != width
    header = NULL;
    while (1) {
        /* home; clear to the end of screen */
        printf("\033[H""\033[J");
        if (!(opt & 0x2)) { // no -t
            const unsigned time_len = sizeof("1234-67-90 23:56:89");

            // STDERR_FILENO is procps3 compat:
            // "watch ls 2>/dev/null" does not detect tty size
            new_width = get_terminal_width(STDERR_FILENO);
            if (new_width != width) {
                width = new_width;
                free(header);
                header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
            }
            if (time_len < width) {
                strftime_YYYYMMDDHHMMSS(
                    header + width - time_len,
                    time_len,
                    /*time_t*:*/ NULL
                );
            }

            // compat: empty line between header and cmd output
            printf("%s\n\n", header);
        }
        fflush_all();
        // 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);
    }
    return 0; // gcc thinks we can reach this :)
}