Linux高级程序设计->文件系统编程课后练习
- 文件操作练习一
编写代码，完成以下功能：
1.创建文件file1，写入字符串“abcdefghijklmn”；
2.创建文件file2，写入字符串“ABCDEFGHIJKLMN”;
3.读取file1中的内容，写入file2，使file2中的字符串内容为“abcdefghijklmn ABCDEFGHIJKLMN”
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
#include<fcntl.h>
#include<sys/types.h>
int main()
{
int fd1,writenum,fd2;
fd1 = open("file1.txt",O_RDWR|O_CREAT);
if(fd1 < 0){
perror("open file1:");
printf("error is %d\n",errno);
}
else
printf("open file1 OK\n");
char* str="abcdefghijklmn";
writenum = write(fd1,str,strlen(str));
if(writenum != strlen(str)){
perror("write file1:");
printf("error is %d\n",errno);
}
else
printf("write OK\n");
char buf[255];
fd2=open("file2.txt",O_RDWR|O_CREAT);
if(fd2 < 0){
perror("open file2:");
printf("error is %d\n",errno);
}
else
printf("open file2 OK\n");
lseek(fd2,15,SEEK_SET);
writenum = write(fd2,"ABCDEFGHIJKLMN",14);
if(writenum != 14 ){
perror("write file2:");
printf("error is %d\n",errno);
}
else
printf("write file2 OK\n");
lseek(fd1,0,SEEK_SET);
lseek(fd2,0,SEEK_SET);
read(fd1,buf,5);
write(fd2,buf,5);
close(fd1);
close(fd2);
return 0;
}
-
文件操作练习二
编写代码，完成以下功能：
1.创建新文件，该文件具有用户读写权限。
2.采用dup/dup2/fcntl复制一个新的文件描述符，通过新文件描述符向文件写入“class_name”字符串；
3.通过原有的文件描述符读取文件中的内容，并且打印显示；
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<errno.h>
#include<fcntl.h>
Int main()
{
int fd,fdcopy,writeNum,readNum；
fd = open(“test.txt”,O_RDWR|O_CREAT);
if(fd < 0){
perror(“open:”);
printf(“error is : %d\n”,errno);
}
else
printf(“open OK\n”);
char str[] = “class_name”;
fscopy=dup(fd);
writeNum = write(fdcopy,str ,strlen(str));
if(weriteNum != strlen(str)){
perror(“writecopy:”);
printf(“error is : %d\n”,errno);
}
else
printf(“write OK\n”);
lseek(fd,0,SEEK_SET);
char buf[]=“”;
readNum = read(fd,buf,strlen(str));
if(readNum != strlen(str)){
perror(“read:”);
printf(“error is : %d\n”,errno);
}
else
printf(“read Ok,the string is :%s\n”,buf);
close(fd);
close(fdcopy);
return 0;
}
- 文件操作练习三
编写程序实现以下功能：
输入文件名称，能够判断文件类型，判断实际用户对该文件具有哪些存取权限；
要求打印出文件类型信息，inode节点编号，链接数目，用户id，组id，文件大小信息；
修改文件的权限为当前用户读写，组内用户读写，组外用户无权限。
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<errno.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
int main(int argc,char* argv[])
{
if(argc < 2){
printf(“two or more permenters;\n”);
}
struct stat statBuf;//复制文件状态
char* str;//文件类型
for(int i = 1; i < argc ;i++){
printf(%s message:\n”,argv[]);
if(lstat(argv[i],&statBuf) < 0)
perror(“latat error \n“);
//判断文件类型
if(S_ISREG(statBuf.st_mode))
str = “regular file”;
else if((S_ISDIR(statBuf.st_mode))
str = “directory file”;
else if((S_ISCHR(statBuf.st_mode))
str = “char device file”;
else if((S_ISFIFO(statBuf.st_mode))
str = “fifo file”;
else if((S_ISBLK(statBuf.st_mode))
str = “blk file”;
else if((S_ISLNK(statBuf.st_mode))
str = “symbolic link file”;
else if((S_ISSOCK(statBuf.st_mode))
str = “socket file”;
printf(“ this file is a %s\n”,str);
//判断存取权限
if(access(argv[i],F_OK) < 0)
perror(“file access error\n”);
else{
if(access(argv[i],R_OK) < 0)
perror(“access R_OK\n”);
else
printf(“user can read %s\n”,argv[i]);
if(access(argv[i],W_OK) < 0)
perror(“access W_OK\n”);
else
printf(“user can write %s\n”,argv[i]);
if(access(argv[i],X_OK) < 0)
perror(“access X_OK\n”);
else
printf(“user can run %s\n”,argv[i]);
}
//打印文件信息
printf(“%s message:\n”,argv[i]);
printf(“file type is %s;\n”,str);
printf(“inode is %ld;\n”,statBuf.st_ino);
printf(“linkNum is %ld;\n”,statBuf.st_nlink);
printf(“uid is %ld;\n”,statBuf.st_uid);
printf(“gid is %ld;\n”,statBuf.st_gid);
printf(“size is %ld;\n”,statBuf.st_size);
printf(“------------------------\n");
//修改文件权限
if(chmod(argv[i],0660) < 0)
printf(“chmod error\n”);
}
return 0;
}
-
文件操作练习四
编写程序实现以下功能：
1.新建文件，设置文件权限屏蔽字为0；
2.建立该文件的硬链接文件，打印硬链接文件的inode节点号和文件大小；
3.建立该文件的软链接文件，打印软链接文件的inode节点号和文件大小；打印软链接文件中的内容；
4.打印源文件的inode节点号，文件大小和链接数目；
5.调用unlink对源文件进行操作，打印源文件链接数目；
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<errno.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
int main()
{
int fd1,fd2,fd3;
struct stat statBuf1,statBuf2,statBuf3;
fd1 = open(“file1”,O_RDWR|O_CREAT);
if(fd1 < 0)
{
perror(“open:”);
printf(“error is :%d\n”.errno);
}
fchmod(fd1,S_IRWXU|S_IRWXG|S_IRWXO);
int writeNum;
writeNum = write(fd1,”123456789”,9);
if(writeNum != 9)
perror(“write error is:%d\n”,errno);
else
printf(“write OK\n”);
umask(0);
int link1 = link(“file1”,”file2”);
if(link1 < 0)
perror(“link1”);
stat(“file2”,&statBuf2);
printf(“hard link file inode :%ld\n”,statBuf2.st_ino);
printf(“hard link file size :%ld\n”,statBuf2.st_size);
int link2 = symlink(“file1”,”file3”);
if(link2 < 0)
perror(“link2”);
lstat(“file3”,&statBuf3);
char str[10];
int readNum = readlink(“file3”,str,10);
if(readNum < 0)
perror(“read error :%d\n”,errno);
else
printf(“read OK\n”);
printf(“symbolic link file inode :%ld\n”,statBuf3.st_ino);
printf(“symbolic link file size :%ld\n”,statBuf3.st_size);
printf(“symbolic link file content :%s\n”,str);
fstat(fd1,&statBuf1);
printf(“file inode :%ld\n”,statBuf1.st_ino);
printf(“file size :%ld\n”,statBuf1.st_size);
printf(“file link number :%d\n”,statBuf1.st_nlink);
if(unlink(“file1”) < 0)
perror(“unlink”);
close(fd1);
return 0;
}
- 文件操作练习五
1.新建/home/user目录；
2.把当前工作路径移至/home/user目录；
3.打印当前工作路径；
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<error.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<dirent.h>
int main()
{
if(mkdir(“/home/user”,0777) < 0)
perror(“mkdir error:%d\n”,errno);
char dir[] = “/home/user”;
chdir(dir);
char dircopy[255];
getcwd(dircopy,255);
printf(“current directory is :%s\n”,dircopy);
rmdir(“/home/user”);
return 0;
}
- 文件操作练习六
编写程序完成以下功能：
1.递归遍历/home目录，打印出所有文件和子目录名称及节点号。
2.判断文件类型，如果是子目录，继续进行递归遍历，直到遍历完所有子目录为止。
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<error.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<dirent.h>
void scan(char* path)
{
char str[255];
DIR *dirpath;
struct dirent *dir;
struct stat statbuf;
dirpath = openddir(path);
if(dirpath)
{
while((dir = readdir(dirpath)))
{
sprintf(str,”%s%s”,path,dirpath->d_name);
if(lstat(str,&statbuf) < 0)
perror(“lstat error”);
if(dir->d_name[0] == ‘.’)
continue;
if(S_ISDIR(statbuf.st_mode))
{
scan(str);
printf(“the dirent name is :%s\n”,dir->d_name);
printf(“the dirent inode is :%d\n”,dir->d_ino);
}
else
{
printf(“the file name is :%s\n”,dir->d_name);
printf(“the file inode is :%d\n”,dir->d_ino);
}
}
}
else
perror(“open dir”);
closedir(dir);
}
int main()
{
scan(“/home”);
return 0;
}
- 作业
编写一个程序，提供一个参数（文件名/路径）
按照下面的要求修改文件权限
设置创建者拥有RWX权限，其他用户只有R-X权限
如果该文件是普通文件 读取并显示该文件的属性/状态信息并创建该文件的一个拷贝
如果该文件是目录文件 显示该目录中的内容及其子目录内容
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<error.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<dirent.h>
void scan(char* path)
{
char str[255];
DIR *dirpath;
struct dirent *dir;
struct stat statbuf;
dirpath = openddir(path);
if(dirpath)
{
while((dir = readdir(dirpath)))
{
sprintf(str,”%s%s”,path,dirpath->d_name);
if(lstat(str,&statbuf) < 0)
perror(“lstat error”);
if(dir->d_name[0] == ‘.’)
continue;
if(S_ISDIR(statbuf.st_mode))
{
scan(str);
printf(“the dirent name is :%s\n”,dir->d_name);
printf(“the dirent inode is :%d\n”,dir->d_ino);
}
else
{
printf(“the file name is :%s\n”,dir->d_name);
printf(“the file inode is :%d\n”,dir->d_ino);
}
}
}
else
perror(“open dir”);
closedir(dir);
}
int main(int argc,char* argv[])
{
int fd;
struct stat statBuf;
char str[255];
for(int i = 0; i < argc; i++)
{
if(stat(argv[i],&statBuf) < 0)
perror(“stat error”);
if(chmod(argv[i],S_IRWXU|S_IROTH|S_IXOTH) < 0)
perror(“chmod error”);
if(S_ISREG(statBuf.st_mode))
{
printf(“this is a regular file\n”);
printf(“%s message:\n”,argv[i]);
printf(“inode is %ld;\n”,statBuf.st_ino);
printf(“linkNum is %ld;\n”,statBuf.st_nlink);
printf(“uid is %ld;\n”,statBuf.st_uid);
printf(“gid is %ld;\n”,statBuf.st_gid);
printf(“size is %ld;\n”,statBuf.st_size);
FILE *fp1,*fp2;
fp1 = fopen(argv[i],”r”);
fp2 = fopen(“filecopy”,”w+”);
while(!feof(fp1))
putc(getc(fp1),fp2);
fclose(fp1);
fclose(fp2);
}
else if(s_IFDIR(statBuf.st_mode))
scan(argv[i]);
else
printf(“this not is a regular file or directory\n”);
}
return 0;
}
