Linux Guard Service-the role, purpose, and characteristics of the parent process identity of the daemon

Let Test2 directly become the Guardian process

[[email protected] 02]# cat test2.c //test2#include<stdio.h>#include<unistd.h>#include<fcntl.h>#include<sys/stat.h>#include<stdlib.h>int main(){        if(daemon(1,1)==-1){                perror("daemon error");                exit(EXIT_FAILURE);        }        int i=0;        while(1){                FILE *fd=fopen("test2.log","a");                fprintf(fd,"%d 1552227\n",i++);                sleep(1);                fclose(fd);        }        return 0;}[[email protected] 02]#

The execution of Test2 has become a test2.log file, and the constantly updated test2.log indicates that it is constantly running

32 155222733 155222734 155222735 155222736 155222737 155222738 155222739 155222740 1552227[[email protected] 02]#

Exit the current terminal, ( no longer prompted for a task in progress ) to enable the new terminal, and then observe Test2.log

The discovery program is still performing normally

Use

View All Daemons

  2761 ?        Sl     0:00  \_ /usr/libexec/evolution-addressbook-factory-subpr  2766 ?        Sl     0:00 /usr/libexec/ibus-x11 --kill-daemon  2837 ?        Sl     0:00 /usr/libexec/gvfsd-network --spawner :1.4 /org/gtk/g  2852 ?        Sl     0:00 /usr/libexec/gvfsd-dnssd --spawner :1.4 /org/gtk/gvf  9158 ?        Ss     0:00 ./test2  9187 ?        Sl     0:00 /usr/sbin/abrt-dbus -t133[[email protected] 02]#

./test2 is a top-level process with no parent process ( unlike the previous-bash as the parent process )

To print information in the process, you can use the method that is output to log, but note the points

1. Write the file close every time, otherwise it is not written in
2. To control the program write log, otherwise it will produce a GB of text log, multiple write log programs can run at the same time may be down the system

Linux Guard Service-the role, purpose, and characteristics of the parent process identity of the daemon