#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

int main(int argc,char **argv){
    pid_t pid=0,ppid=0;
    uid_t uid=0,euid=0;
    gid_t gid=0,egid=0;
    
    pid=getpid();//程序ID
    ppid=getppid();//父程序ID
    uid=getuid();//實際使用者ID
    euid=geteuid();//有效使用者ID
    gid=getgid();//實際組ID
    egid=getegid();//有效組ID 
    
	printf("%u,%u,%u,%u,%u,%u\n",pid,ppid,uid,euid,gid,egid);
	return 0;
}
 

processID.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

int global;

int main(int argc,char **argv){
    pid_t pid;
    int stack=1;
    int *heap=NULL;
    heap=(int *)malloc(sizeof(int));
    *heap=2;
	pid=fork();
    
    if(pid<0){
    	perror("fork()");
    	exit(1);
    }else if(pid==0){
    	global++;
    	stack++;
    	(*heap)++;
    	printf("The child ,pid is %u,stack:%d,heap:%d,global:%d.\n",getpid(),stack,*heap,global);
    }else{
    	sleep(2);
    	printf("The parent ,pid is %u,stack:%d,heap:%d,global:%d.\n",getpid(),stack,*heap,global);
    }
    exit(0);
}
 

processCreat.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

int global;

int main(int argc,char **argv){
     pid_t pd=0;
    int count=0;
    if(argc<2){
    	perror("Usage Error !\n");
    	exit(1);
    }
    for(count=1;count<argc;count++){
    	pd=fork();
    	if(pd<0){
    		perror("fork()");
    		exit(1);
    	}else if(pd==0){
    		printf("Child Start PID=%d\t*****\n",getpid());
    		execl("/bin/ls","ls",argv[count],NULL);
    		perror("execl()");
    		exit(1);
    	}else{
    		//wait(1);
    		printf("Child End PID=%d\t*****\n",getpid());
    	}
    	exit(0);
    }
}
 

processUseShell.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
//#include <apue.h>

int main(int argc,char **argv){
    char *command=NULL;
	int flag=0;
	command=(char *)malloc(1024*sizeof(char));
	memset(command,0,1024*sizeof(char));
	while(1){
		printf("[email protected]");
		if(fgets(command,100,stdin)!=NULL){
			if(strcmp(command,"exit\n")==0){
				puts("quit successful!");
				break;
			}
			flag=system(command);
			if(flag==-1){
				perror("fork()");
				exit(1);
			}
			memset(command,0,100);
		}
	}
	free(command);
	command=NULL;
	exit(0);
}