Code that has to end no matter what Post: 303022399

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Top Forums Shell Programming and Scripting Code that has to end no matter what Post 303022399 by drysdalk on Friday 31st of August 2018 06:22:25 AM

08-31-2018

Registered User

Hello,

I'm not 100% clear on what you might mean here, but I see two possibilities. A script will normally exit either when the last command it contains is executed, or when an exit statement is explicitly executed. So you don't really have to worry about "making sure it always ends" - by its very nature, a script will end so long as it contains no loop or logic that would cause it to keep running.

However, if what you're meaning here is that you want a command in your script to always exit after a certain amount of time to prevent it from running indefinitely, then you could try something like this:

Code:

#!/bin/bash

command="/usr/bin/yes"
maxruntime=10

"$command" >/dev/null 2>/dev/null &
watchpid=$!

/usr/bin/sleep "$maxruntime"

if [ -d "/proc/$watchpid" ]
then
        echo "Max runtime exceeded, killing PID $watchpid"

        if /bin/kill -9 "$watchpid" >/dev/null 2>/dev/null
        then
                echo "Killed."
                exit 0
        else
                echo "Could not kill, please investigate manually."
                exit 1
        fi
fi

Here you define command as the full command you want to run, and maxruntime as the maximum number of seconds it can be permitted to run for. The script then executes the command specified in the variable command in the background, with all output re-directed to /dev/null. It then waits for maxruntime seconds, and if the process still exists, it will attempt to kill it and show you the result.

Note that in its current form the script will always wait for maxruntime seconds no matter what, so even if your command has exited before then the script will wait at least that long. You could amend that easily enough though, but this is just to give you an idea of how this might work.

Hope this helps - if not, or if I've not quite grasped what you're actually struggling with here, then if you could provide a bit more info I'd be happy to help further.

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LEARN ABOUT NETBSD

cpuset_clr

CPUSET(3)						   BSD Library Functions Manual 						 CPUSET(3)

NAME

     cpuset_create, cpuset_destroy, cpuset_zero, cpuset_set, cpuset_clr, cpuset_isset, cpuset_size -- dynamic CPU sets

SYNOPSIS

     #include <sched.h>

     cpuset_t *
     cpuset_create(void);

     void
     cpuset_destroy(cpuset_t *set);

     void
     cpuset_zero(cpuset_t *set);

     int
     cpuset_set(cpuid_t cpu, cpuset_t *set);

     int
     cpuset_clr(cpuid_t cpu, cpuset_t *set);

     int
     cpuset_isset(cpuid_t cpu, const cpuset_t *set);

     size_t
     cpuset_size(const cpuset_t *set);

DESCRIPTION

     This section describes the functions used to create, set, use and destroy the dynamic CPU sets.

     This API can be used with the POSIX threads, see pthread(3) and affinity(3).

     The ID of the primary CPU in the system is 0.

FUNCTIONS

     cpuset_create()
	      Allocates and initializes a clean CPU-set.  Returns the pointer to the CPU-set, or NULL on failure.

     cpuset_destroy(set)
	      Destroy the CPU-set specified by set.

     cpuset_zero(set)
	      Makes the CPU-set specified by set clean, that is, memory is initialized to zero bytes, and none of the CPUs set.

     cpuset_set(cpu, set)
	      Sets the CPU specified by cpu in set.  Returns zero on success, and -1 if cpu is invalid.

     cpuset_clr(cpu, set)
	      Clears the CPU specified by cpu in the CPU-set set.  Returns zero on success, and -1 if cpu is invalid.

     cpuset_isset(cpu, set)
	      Checks if CPU specified by cpu is set in the CPU-set set.  Returns the positive number if set, zero if not set, and -1 if cpu is
	      invalid.

     cpuset_size(set)
	      Returns the size in bytes of CPU-set specified by set.

SEE ALSO

     affinity(3), pset(3), sched(3), schedctl(8), kcpuset(9)

HISTORY

     The dynamic CPU sets appeared in NetBSD 5.0.

BSD
								 November 2, 2011							       BSD