Set Timeout For A Shell Command

虫子樱桃

老外写的，觉得很不错
原帖 http://www.cyberciti.biz/faq/she ... d-under-alarmclock/

1. :
   
2. ##########################################################################
   
3. # Shellscript:        timeout - set timeout for a command
   
4. # Author     :        Heiner Steven <heiner.steven@odn.de>
   
5. # Date       :        29.07.1999
   
6. # Category   :        File Utilities
   
7. # Requires   :
   
8. # SCCS-Id.   :        @(#) timeout        1.3 03/03/18
   
9. ##########################################################################
   
10. # Description
    
11. #    o        Runs a command, and terminates it (by sending a signal) after
    
12. #        a specified time period
    
13. #    o        This command first starts itself as a "watchdog" process in the
    
14. #        background, and then runs the specified command.
    
15. #        If the command did not terminate after the specified
    
16. #        number of seconds, the "watchdog" process will terminate
    
17. #        the command by sending a signal.
    
18. #
    
19. # Notes
    
20. #    o        Uses the internal command line argument "-p" to specify the
    
21. #        PID of the process to terminate after the timeout to the
    
22. #        "watchdog" process.
    
23. #    o        The "watchdog" process is invoked by the name "$0", so
    
24. #        "$0" must be a valid path to the script.
    
25. #    o        If this script runs in the environment of the login shell
    
26. #        (i.e. it was invoked using ". timeout command...") it will
    
27. #        terminate the login session.
    
28. ##########################################################################
    
29. 
    
30. PN=`basename "$0"`                        # Program name
    
31. VER='1.3'
    
32. 
    
33. TIMEOUT=5                                # Default [seconds]
    
34. 
    
35. Usage () {
    
36.     echo >&2 "$PN - set timeout for a command, $VER
    
37. usage: $PN [-t timeout] command [argument ...]
    
38.      -t: timeout (in seconds, default is $TIMEOUT)"
    
39.     exit 1
    
40. }
    
41. 
    
42. Msg () {
    
43.     for MsgLine
    
44.     do echo "$PN: $MsgLine" >&2
    
45.     done
    
46. }
    
47. 
    
48. Fatal () { Msg "$@"; exit 1; }
    
49. 
    
50. while [ $# -gt 0 ]
    
51. do
    
52.     case "$1" in
    
53.         -p)        ParentPID=$2; shift;;        # Used internally!
    
54.         -t)        Timeout="$2"; shift;;
    
55.         --)        shift; break;;
    
56.         -h)        Usage;;
    
57.         -*)        Usage;;
    
58.         *)        break;;                        # First file name
    
59.     esac
    
60.     shift
    
61. done
    
62. 
    
63. : ${Timeout:=$TIMEOUT}                        # Set default [seconds]
    
64. 
    
65. if [ -z "$ParentPID" ]
    
66. then
    
67.     # This is the first invokation of this script.
    
68.     # Start "watchdog" process, and then run the command.
    
69.     [ $# -lt 1 ] && Fatal "please specify a command to execute"
    
70.     "$0" -p $ -t $Timeout &                # Start watchdog
    
71.     #echo >&2 "DEBUG: process id is $"
    
72.     exec "$@"                                # Run command
    
73.     exit 2                                # NOT REACHED
    
74. else
    
75.     # We run in "watchdog" mode, $ParentPID contains the PID
    
76.     # of the process we should terminate after $Timeout seconds.
    
77.     [ $# -ne 0 ] && Fatal "please do not use -p option interactively"
    
78. 
    
79.     #echo >&2 "DEBUG: $: parent PID to terminate is $ParentPID"
    
80. 
    
81.     exec >/dev/null 0<&1 2>&1        # Suppress error messages
    
82.     sleep $Timeout
    
83.     kill $ParentPID &&                        # Give process time to terminate
    
84.             (sleep 2; kill -1 $ParentPID) &&
    
85.         (sleep 2; kill -9 $ParentPID)
    
86.     exit 0
    
87. fi

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