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 //config:config WATCH
11 //config: bool "watch (4.4 kb)"
12 //config: default y
13 //config: help
14 //config: watch is used to execute a program periodically, showing
15 //config: output to the screen.
16
17 //applet:IF_WATCH(APPLET(watch, BB_DIR_BIN, BB_SUID_DROP))
18
19 //kbuild:lib-$(CONFIG_WATCH) += watch.o
20
21 //usage:#define watch_trivial_usage
22 //usage: "[-n SEC] [-t] PROG ARGS"
23 //usage:#define watch_full_usage "\n\n"
24 //usage: "Run PROG periodically\n"
25 //usage: "\n -n SEC Period (default 2)"
26 //usage: "\n -t Don't print header"
27 //usage:
28 //usage:#define watch_example_usage
29 //usage: "$ watch date\n"
30 //usage: "Mon Dec 17 10:31:40 GMT 2000\n"
31 //usage: "Mon Dec 17 10:31:42 GMT 2000\n"
32 //usage: "Mon Dec 17 10:31:44 GMT 2000"
33
34 /* BB_AUDIT SUSv3 N/A */
35 /* BB_AUDIT GNU defects -- only option -n is supported. */
36
37 #include "libbb.h"
38
39 #define ESC "\033"
40
41 // procps 2.0.18:
42 // watch [-d] [-n seconds]
43 // [--differences[=cumulative]] [--interval=seconds] command
44 //
45 // procps-3.2.3:
46 // watch [-dt] [-n seconds]
47 // [--differences[=cumulative]] [--interval=seconds] [--no-title] command
48 //
49 // (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
50
51 int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
watch_main(int argc UNUSED_PARAM,char ** argv)52 int watch_main(int argc UNUSED_PARAM, char **argv)
53 {
54 duration_t period;
55 char *period_str = (char*) "2";
56 unsigned opt;
57 unsigned width, new_width;
58 char *header;
59 char *cmd;
60
61 #if 0 // maybe ENABLE_DESKTOP?
62 // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
63 close(STDIN_FILENO);
64 xopen("/dev/null", O_RDONLY);
65 #endif
66
67 // "+": stop at first non-option (procps 3.x only); -n NUM
68 // at least one param
69 opt = getopt32(argv, "^+" "dtn:" "\0" "-1", &period_str);
70 argv += optind;
71
72 // watch from both procps 2.x and 3.x does concatenation. Example:
73 // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
74 cmd = *argv;
75 while (*++argv)
76 cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
77
78 period = parse_duration_str(period_str);
79 width = (unsigned)-1; // make sure first time new_width != width
80 header = NULL;
81 while (1) {
82 /* home; clear to the end of screen */
83 printf(ESC"[H" ESC"[J");
84 if (!(opt & 0x2)) { // no -t
85 const unsigned time_len = sizeof("1234-67-90 23:56:89");
86
87 // STDERR_FILENO is procps3 compat:
88 // "watch ls 2>/dev/null" does not detect tty size
89 new_width = get_terminal_width(STDERR_FILENO);
90 if (new_width != width) {
91 width = new_width;
92 free(header);
93 header = xasprintf("Every"
94 " %"IF_FLOAT_DURATION(".1")DURATION_FMT"s:"
95 " %-*s",
96 period,
97 (int)width, cmd
98 );
99 }
100 if (time_len < width) {
101 strftime_YYYYMMDDHHMMSS(
102 header + width - time_len,
103 time_len,
104 /*time_t*:*/ NULL
105 );
106 }
107
108 // compat: empty line between header and cmd output
109 printf("%s\n\n", header);
110 }
111 fflush_all();
112 // TODO: 'real' watch pipes cmd's output to itself
113 // and does not allow it to overflow the screen
114 // (taking into account linewrap!)
115 system(cmd);
116 sleep_for_duration(period);
117 }
118 return 0; // gcc thinks we can reach this :)
119 }
120