CODEWITHSUNDEEP
cbashservicedaemon
Odko
Odko

Reputation: 151

Background programming in C

I'm trying to create a background program that has main config file which contains another config file locations and execute each of them. For example: if main_config.conf:

/home/conf1
/home/conf2

i want to execute ./background_pro /home/conf1 and ./background_pro /home/conf2 in background. How do i do that ? I'm using below structure.Thank you

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>

int main(void) {

        /* Our process ID and Session ID */
        pid_t pid, sid;

        /* Fork off the parent process */
        pid = fork();
        if (pid < 0) {
                exit(EXIT_FAILURE);
        }
        /* If we got a good PID, then
           we can exit the parent process. */
        if (pid > 0) {
                exit(EXIT_SUCCESS);
        }

        /* Change the file mode mask */
        umask(0);

        /* Open any logs here */        

        /* Create a new SID for the child process */
        sid = setsid();
        if (sid < 0) {
                /* Log the failure */
                exit(EXIT_FAILURE);
        }



        /* Change the current working directory */
        if ((chdir("/")) < 0) {
                /* Log the failure */
                exit(EXIT_FAILURE);
        }

        /* Close out the standard file descriptors */
        close(STDIN_FILENO);
        close(STDOUT_FILENO);
        close(STDERR_FILENO);

        /* Daemon-specific initialization goes here */

        /* The Big Loop */
        while (1) {
           /* Do some task here ... */

           sleep(30); /* wait 30 seconds */
        }
   exit(EXIT_SUCCESS);
}

Upvotes: 0

Views: 482

Answers (2)

Hank Chang
Hank Chang

Reputation: 211

Just append an '&' at the rear of shell command, then the command will run in background. I think, this may be what you want: daemon.bash

#!bash

# to stop a sub process
if [ "x$1" = "x-stop" ]; then
    if [ "x$2" = "xsub1" ]; then
        kill `cat sub1.pid`
    elif [ "x$2" = "xsub2" ]; then
        kill `cat sub2.pid`
    fi
    exit
fi

# to start sub processes
conf1=`head -1 main_config.conf`
conf2=`head -2 main_config.conf | tail -1`
nohup ./background_pro $conf1 &
pid1=$!
echo "$pid1" > sub1.pid
nohup ./background_pro $conf2 &
pid2=$!
echo "$pid2" > sub2.pid

Run the demon:

nohup ./daemon.bash &

The nohup will keep the program running even you turn off the terminal.

Stop sub process 1:

./daemon.bash -stop sub1

Upvotes: 1

JD_GRINDER
JD_GRINDER

Reputation: 354

A background program might be what linux users call a "Daemon" program. Please look here on Creating a daemon in Linux where you can find a plethora of information on how to begin writing your own Daemon. For parsing command line arguments, i recommend reading the GNU c library manual for getopt().

Upvotes: 0

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