如何限制BASH脚本的运行时间

请参阅 http://www.pixelbeat.org/scripts/timeout 脚本,其功能已集成到较新的coreutils中:

#!/bin/sh

# Execute a command with a timeout

# License: LGPLv2
# Author:
#    http://www.pixelbeat.org/
# Notes:
#    Note there is a timeout command packaged with coreutils since v7.0
#    If the timeout occurs the exit status is 124.
#    There is an asynchronous (and buggy) equivalent of this
#    script packaged with bash (under /usr/share/doc/ in my distro),
#    which I only noticed after writing this.
#    I noticed later again that there is a C equivalent of this packaged
#    with satan by Wietse Venema, and copied to forensics by Dan Farmer.
# Changes:
#    V1.0, Nov  3 2006, Initial release
#    V1.1, Nov 20 2007, Brad Greenlee <brad@footle.org>
#                       Make more portable by using the 'CHLD'
#                       signal spec rather than 17.
#    V1.3, Oct 29 2009, Ján Sáreník <jasan@x31.com>
#                       Even though this runs under dash,ksh etc.
#                       it doesn't actually timeout. So enforce bash for now.
#                       Also change exit on timeout from 128 to 124
#                       to match coreutils.
#    V2.0, Oct 30 2009, Ján Sáreník <jasan@x31.com>
#                       Rewritten to cover compatibility with other
#                       Bourne shell implementations (pdksh, dash)

if [ "$#" -lt "2" ]; then
    echo "Usage:   `basename $0` timeout_in_seconds command" >&2
    echo "Example: `basename $0` 2 sleep 3 || echo timeout" >&2
    exit 1
fi

cleanup()
{
    trap - ALRM               #reset handler to default
    kill -ALRM $a 2>/dev/null #stop timer subshell if running
    kill $! 2>/dev/null &&    #kill last job
      exit 124                #exit with 124 if it was running
}

watchit()
{
    trap "cleanup" ALRM
    sleep $1& wait
    kill -ALRM $$
}

watchit $1& a=$!         #start the timeout
shift                    #first param was timeout for sleep
trap "cleanup" ALRM INT  #cleanup after timeout
"$@"& wait $!; RET=$?    #start the job wait for it and save its return value
kill -ALRM $a            #send ALRM signal to watchit
wait $a                  #wait for watchit to finish cleanup
exit $RET                #return the value

以下脚本显示了如何使用后台任务完成此操作。第一部分在10秒的限制后终止60秒的进程。第二次尝试终止已退出的进程。请记住,如果你将超时设置得很高,进程ID可能会滚动,你会杀死错误的进程,但这更多的是一个理论问题——超时必须是 非常 大,你必须开始一个 许多 过程。

#!/usr/bin/bash

sleep 60 &
pid=$!
sleep 10
kill -9 $pid

sleep 3 &
pid=$!
sleep 10
kill -9 $pid

这是我的Cygwin盒子上的输出:

$ ./limit10
./limit10: line 9:  4492 Killed sleep 60
./limit10: line 11: kill: (4560) - No such process

如果你只想等到流程完成,你需要进入一个循环并检查。这有点不准确,因为 sleep 1 而其他命令实际上需要一秒钟以上(但不会太多)。使用此脚本替换上面的第二部分(“ echo $proc “和” date “命令是用于调试的,我不希望在最终解决方案中使用它们)。

#!/usr/bin/bash

date
sleep 3 &
pid=$!
((lim = 10))
while [[ $lim -gt 0 ]] ; do
    sleep 1
    proc=$(ps -ef | awk -v pid=$pid '$2==pid{print}{}')
    echo $proc
    ((lim = lim - 1))
    if [[ -z "$proc" ]] ; then
            ((lim = -9))
    fi
done
date
if [[ $lim -gt -9 ]] ; then
    kill -9 $pid
fi
date

它基本上是循环的,每秒检查进程是否仍在运行。如果没有,它将使用一个特殊值退出循环,以避免尝试杀死孩子。否则,它会超时并杀死孩子。

这是a的输出 sleep 3 :

Mon Feb  9 11:10:37 WADT 2009
pax 4268 2476 con 11:10:37 /usr/bin/sleep
pax 4268 2476 con 11:10:37 /usr/bin/sleep
Mon Feb  9 11:10:41 WADT 2009
Mon Feb  9 11:10:41 WADT 2009

以及a sleep 60 :

Mon Feb  9 11:11:51 WADT 2009
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
pax 4176 2600 con 11:11:51 /usr/bin/sleep
Mon Feb  9 11:12:03 WADT 2009
Mon Feb  9 11:12:03 WADT 2009
./limit10: line 20:  4176 Killed sleep 60

查看 this link 这个想法就是你会跑 myscript.sh 作为脚本的子进程,记录其PID,如果运行时间过长,则将其终止。

timeout 30s YOUR_COMMAND COMMAND_ARGUMENTS

以下是coreutils下的所有“超时”选项:

$ timeout --help
Usage: timeout [OPTION] DURATION COMMAND [ARG]...
  or:  timeout [OPTION]
Start COMMAND, and kill it if still running after DURATION.

Mandatory arguments to long options are mandatory for short options too.
      --preserve-status
                 exit with the same status as COMMAND, even when the
                   command times out
      --foreground
                 when not running timeout directly from a shell prompt,
                   allow COMMAND to read from the TTY and get TTY signals;
                   in this mode, children of COMMAND will not be timed out
  -k, --kill-after=DURATION
                 also send a KILL signal if COMMAND is still running
                   this long after the initial signal was sent
  -s, --signal=SIGNAL
                 specify the signal to be sent on timeout;
                   SIGNAL may be a name like 'HUP' or a number;
                   see 'kill -l' for a list of signals
      --help     display this help and exit
      --version  output version information and exit

DURATION is a floating point number with an optional suffix:
's' for seconds (the default), 'm' for minutes, 'h' for hours or 'd' for days.

If the command times out, and --preserve-status is not set, then exit with
status 124.  Otherwise, exit with the status of COMMAND.  If no signal
is specified, send the TERM signal upon timeout.  The TERM signal kills
any process that does not block or catch that signal.  It may be necessary
to use the KILL (9) signal, since this signal cannot be caught, in which
case the exit status is 128+9 rather than 124.

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/timeout>
or available locally via: info '(coreutils) timeout invocation'

您可以将该命令作为后台作业运行(即使用“&”),将bash变量用于“上次命令运行的pid”,休眠必要的时间,然后运行 kill 有了这个pid。