Linux下的C编程程序源代码

hobby! · 发表于 2004-11-22 12:17:28

#include <sys/types.h>

#include <stdio.h>

#include <unistd.h>

int main(void)

{

pid_t pid;

if((pid=vfork())<0)

{

printf("fork error! \n");

exit(1);

}

else if(pid==0)

{

printf("Child process PID: %d.\n",getpid());

setenv("PS1", "CHILD\\$", 1);

printf("Process%4d: calling exec.\n",getpid());

if(execl("/bin/sh", "/bin/sh", "arg2", NULL)<0)

{

printf("Process%4d: execle error!\n",getpid());

exit(0);

}

printf("Process%4d: You should never see this because the child is already gone. \n",

getpid());

printf("Precess%4d: The child process is exiting.");

}

else

{

printf("Parent process PID:%4d.\n", getpid());

printf("Process%4d: The parent has fork process %d.\n", pid);

printf("Process%4d: The child has called exec or has exited.\n", getpid());

}

return 0;

}

hobby! · 发表于 2004-11-22 12:18:16

#include <sys/types.h>

#include <sys/wait.h>

#include <stdio.h>

void h_exit(int status);

int main(void)

{

pid_t pid;

int status;

if((pid=fork())<0)

{

        printf("fork error!\n");

        exit(0);

}

else if(pid==0)

        exit(7);

if(wait(&status)!=pid)

{

        printf("wait error!\n");

        exit(0);

}

h_exit(status);

if((pid=fork())<0)

{

        printf("fork error!\n");

        exit(0);

}

else if(pid==0)

        exit(1);

if(wait(&status)!=pid)

{

        printf("wait error!\n");

        exit(0);

}

h_exit(status);

if((pid=fork())<0)

{

        printf("fork error!\n");

        exit(0);

}

else if(pid==0)



if(wait(&status)!=pid)

{

        printf("wait error!\n");

        exit(0);

}

h_exit(status);

exit(0);

}

void h_exit(int status)

{

if(WIFEXITED(status))

        printf("normal termination, exit status=%d .\n", WEXITSTATUS(status));

else if(WIFSIGNALED(status))

        printf("abnormal termination, exit status=%d. \n", WTERMSIG(status));

}

hobby! · 发表于 2004-11-22 12:20:51

#include <sys/types.h>

#include <sys/wait.h>

#include <sys/resource.h>

#include <stdio.h>

#include <unistd.h>

#include <stdarg.h>

#include <unistd.h>

#include <stdlib.h>

void waitchildren(int signum);

void h_exit(int status);

int main(void)

{

pid_t pid;

int status;

if((pid=fork())<0)

{

        printf("fork error!\n");

        exit(0);

}

else if(pid==0)

{

        printf("Hello from the child process%4d!\n", getpid());

        setenv("PS1", "CHILD \ \ $", 1);

        printf("Process%4d: I’m calling exec. \n", getpid());

execl("/bin/sh", "/bin/sh", NULL);

printf("Process%4d: You should never see this because the child is already gone.\n", getpid());

}

else if(pid!=-1)

{

        printf("Hello from the parent process%4d!\n", getpid());

        printf("Process%4d: The parent has forked process %d. \n", getpid(),pid);

printf("Process%4d: The parent is waiting for the child to exit.\n", getpid());

wait4(pid, &status, 0, NULL);

h_exit(status);

}

return 0;

}

void h_exit(int status)

{

if(WIFEXITED(status))

        printf("normal termination, exit status=%d .\n", WEXITSTATUS(status));

else if(WIFSIGNALED(status))

        printf("abnormal termination, exit status=%d. \n", WTERMSIG(status));

}

hobby! · 发表于 2004-11-22 12:21:31

#include <sys/types.h>

#include <stdio.h>

#include <unistd.h>

void forkerror(void);

void execerror(void);

int main(void)

{

pid_t pid;

if((pid=vfork())<0)

{

atexit(forkerror);

}

else if(pid==0)

{

printf("Child process PID: %d.\n",getpid());

setenv("PS1", "CHILD\\$", 1);

printf("Process%4d: calling exec.\n",getpid());

if(execl("/bin/sh", "/bin/sh", "arg2", NULL)<0)

{

atexit(execerror);

}

printf("Process%4d: You should never see this because the child is already gone. \n",

getpid());

printf("Precess%4d: The child process is exiting.");

}

else

{

printf("Parent process PID:%4d.\n", getpid());

printf("Process%4d: The parent has fork process %d.\n", pid);

printf("Process%4d: The child has called exec or has exited.\n", getpid());

}

return 0;

}

void forkerror(void)

{

printf("fork error!\n");

exit(1);

}

void execerror(void)

{

printf("exec error!\n");

exit(1);

}

hobby! · 发表于 2004-11-22 12:23:08

#include <sys/types.h>

#include <stdio.h>

#include <unistd.h>

void forkerror(void);

void execerror(void);

int main(void)

{

pid_t pid;

if((pid=vfork())<0)

{

atexit(forkerror);

}

else if(pid==0)

{

printf("Child process PID: %d.\n",getpid());

setenv("PS1", "CHILD\\$", 1);

printf("Process%4d: calling exec.\n",getpid());

if(execl("/bin/sh", "/bin/sh", "arg2", NULL)<0)

{

atexit(execerror);

}

printf("Process%4d: You should never see this because the child is already gone. \n",

getpid());

printf("Precess%4d: The child process is exiting.");

}

else

{

printf("Parent process PID:%4d.\n", getpid());

printf("Process%4d: The parent has fork process %d.\n", pid);

printf("Process%4d: The child has called exec or has exited.\n", getpid());

}

return 0;

}

void forkerror(void)

{

printf("fork error!\n");

exit(1);

}

void execerror(void)

{

printf("exec error!\n");

exit(1);

}

hobby! · 发表于 2004-11-22 12:31:24

#include <sys/types.h>

#include <sys/wait.h>

#include <stdio.h>

void h_exit(int status);

static void forkerror(void);

static void waiterror(void);

int main(void)

{

pid_t pid;

int status;

if((pid=fork())<0)

{

        atexit(forkerror);

}

else if(pid==0)

        abort();

if(wait(&status)!=pid)

{

        atexit(waiterror);

}

h_exit(status);

exit(0);

}

void h_exit(int status)

{

if(WIFEXITED(status))

        printf("normal termination, exit status=%d .\n", WEXITSTATUS(status));

else if(WIFSIGNALED(status))

        printf("abnormal termination, exit status=%d. \n", WTERMSIG(status));

}

void forkerror(void)

{

printf("fork error!\n");

}

void waiterror(void)

{

printf("wait error!\n");

}

hobby! · 发表于 2004-11-22 12:38:18

#include <sys/types.h>

#include <sys/stat.h>

#include <stdio.h>

#include <unistd.h>

#include <stdarg.h>

#include <fcntl.h>

#include <stdlib.h>

#include <errno.h>

void enhancedperms(void);

void normalperms(void);

void tryopen(void);

int ruid, euid;

int main(void)

{

ruid=getuid();

euid=geteuid();

normalperms();

if(ruid==euid)

{

        printf("euid%4d: Warning:this program wasn;t marked setuid in the filesystem \n", euid);

        printf("euid%4d: or you running the program ar root.\n", euid);

}

tryopen();

enhancedperms();

tryopen();

normalperms();

printf("euid%4d: Exiting now. \n", euid);

return 0;

}

void enhancedperms(void)

{

if(seteuid(euid)==-1)

{

        printf("euid%4d: Railed to switch to enhanced permissions:%s.\n", euid, sys_errlist[errno]);

        exit(255);

}

else

{

        printf("euid%4d: Switched to enhanced permissions. \n");

}

}

void normalperms(void)

{

if(seteuid(ruid)==-1)

{

        printf("euid%4d: Failed to switch to normal permissions: %s. \n", euid, sys_errlist[errno]);

        exit(255);

}

else

{

        printf("euid%4d: Switched to enhanced permissions. \n");

}

}

void tryopen(void)

{

char *filename="/etc/shadow";

int result;

if(result=open(filename, O_RDONLY)==-1)

{

printf("euid%4d: Open failed: %s.\n", euid, sys_errlist[errno]);

}

else

{

printf("euid%4d: Open was successful.\n", euid);

close(result);

}

}

jiangbo409 · 发表于 2004-11-24 14:30:08

这是干吗呢?

hobby! · 发表于 2004-11-24 22:13:25

这里请大家不要回贴！！！

hobby! · 发表于 2004-11-24 22:13:44

这里请大家不要回贴！！！

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