Linux C语言 36-文件处理补充

本节关键字：C语言 文件操作，文件处理，文件创建，文件信息，文件删除，目录创建，目录信息，目录遍历，目录递归遍历
相关C库函数：access、mkdir、opendir、chdir、readdir、closedir、rm、stat等

声明：时间有限，目前仅将相关库函数记录下来，后期慢慢完善用法及例程，感兴趣的小伙伴可以先关注，有更新就会提醒哦~

判断文件是否存在

#include <unistd.h>
int access(const char *pathname, int mode);

创建目录

#include <sys/stat.h>
#include <sys/types.h>
int mkdir(const char *pathname, mode_t mode);

获取目录的文件描述符

#include <sys/types.h>
#include <dirent.h>
int dirfd(DIR *dirp);

打开目录

#include <sys/types.h>
#include <dirent.h>
DIR *opendir(const char *name);
DIR *fdopendir(int fd);

读取/遍历目录

#include <dirent.h>
struct dirent 
{ino_t          d_ino;       /* inode number */off_t          d_off;       /* offset to the next dirent */unsigned short d_reclen;    /* length of this record */unsigned char  d_type;      /* type of file; not supportedby all file system types */char           d_name[256]; /* filename */
};
int readdir(unsigned int fd, struct old_linux_dirent *dirp, unsigned int count);
struct dirent *readdir(DIR *dirp);
int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);

进入子目录

#include <unistd.h>
int chdir(const char *path);
int fchdir(int fd);

关闭目录

#include <sys/types.h>
#include <dirent.h>
int closedir(DIR *dirp);

删除文件/目录

#include <stdio.h>
int remove(const char *pathname);

目录指针操作

#include <sys/types.h>
#include <dirent.h>
void rewinddir(DIR *dirp);#include <dirent.h>
int scandir(const char *dirp, struct dirent ***namelist,int (*filter)(const struct dirent *),int (*compar)(const struct dirent **, const struct dirent **));
int alphasort(const void *a, const void *b);
int versionsort(const void *s, const void *b);#include <dirent.h>
void seekdir(DIR *dirp, long offset);#include <dirent.h>
long telldir(DIR *dirp);

例程

#define _SVID_SOURCE
/* print files in current directory in reverse order */
#include <dirent.h>
int main(void)
{struct dirent **namelist;int n;n = scandir(".", &namelist, 0, alphasort);if (n < 0){perror("scandir");}else {while (n--) {printf("%s\n", namelist[n]->d_name);free(namelist[n]);}free(namelist);}return 0;
}

获取文件/目录信息

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
struct stat  
{   dev_t       st_dev;     /* ID of device containing file - 文件所在设备的ID*/  ino_t       st_ino;     /* inode number - 节点号*/    mode_t      st_mode;    /* protection - 保护模式?*/    nlink_t     st_nlink;   /* number of hard links - 链向此文件的连接数(硬连接)*/    uid_t       st_uid;     /* user ID of owner - 所有者的用户ID*/    gid_t       st_gid;     /* group ID of owner - 所有者的组ID*/    dev_t       st_rdev;    /* device ID (if special file) - 设备号，针对设备文件*/    off_t       st_size;    /* total size, in bytes - 文件大小，字节为单位*/    blksize_t   st_blksize; /* blocksize for filesystem I/O - 系统块的大小*/    blkcnt_t    st_blocks;  /* number of blocks allocated - 文件所占块数*/    time_t      st_atime;   /* time of last access - 最后访问时间*/    time_t      st_mtime;   /* time of last modification -最近修改时间*/    time_t      st_ctime;   /* time of last status change - 上次状态更改的时间*/    
};
int stat(const char *path, struct stat *buf);
int fstat(int fd, struct stat *buf);
int lstat(const char *path, struct stat *buf);S_ISREG(m)  is it a regular file?
S_ISDIR(m)  directory?
S_ISCHR(m)  character device?
S_ISBLK(m)  block device?
S_ISFIFO(m) FIFO (named pipe)?
S_ISLNK(m)  symbolic link? (Not in POSIX.1-1996.)
S_ISSOCK(m) socket? (Not in POSIX.1-1996.)S_IFMT     0170000   bit mask for the file type bit fields
S_IFSOCK   0140000   socket
S_IFLNK    0120000   symbolic link
S_IFREG    0100000   regular file
S_IFBLK    0060000   block device
S_IFDIR    0040000   directory
S_IFCHR    0020000   character device
S_IFIFO    0010000   FIFO
S_ISUID    0004000   set UID bit
S_ISGID    0002000   set-group-ID bit (see below)
S_ISVTX    0001000   sticky bit (see below)
S_IRWXU    00700     mask for file owner permissions
S_IRUSR    00400     owner has read permission
S_IWUSR    00200     owner has write permission
S_IXUSR    00100     owner has execute permission
S_IRWXG    00070     mask for group permissions
S_IRGRP    00040     group has read permission
S_IWGRP    00020     group has write permission
S_IXGRP    00010     group has execute permission
S_IRWXO    00007     mask for permissions for others (not in group)
S_IROTH    00004     others have read permission
S_IWOTH    00002     others have write permission
S_IXOTH    00001     others have execute permission

例程

#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{struct stat sb;if (argc != 2) {fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);exit(EXIT_FAILURE);}if (stat(argv[1], &sb) == -1) {perror("stat");exit(EXIT_SUCCESS);}printf("File type:                ");switch (sb.st_mode & S_IFMT) {case S_IFBLK:  printf("block device\n");            break;case S_IFCHR:  printf("character device\n");        break;case S_IFDIR:  printf("directory\n");               break;case S_IFIFO:  printf("FIFO/pipe\n");               break;case S_IFLNK:  printf("symlink\n");                 break;case S_IFREG:  printf("regular file\n");            break;case S_IFSOCK: printf("socket\n");                  break;default:       printf("unknown?\n");                break;}printf("I-node number:            %ld\n", (long) sb.st_ino);printf("Mode:                     %lo (octal)\n",(unsigned long) sb.st_mode);printf("Link count:               %ld\n", (long) sb.st_nlink);printf("Ownership:                UID=%ld   GID=%ld\n",(long) sb.st_uid, (long) sb.st_gid);printf("Preferred I/O block size: %ld bytes\n",(long) sb.st_blksize);printf("File size:                %lld bytes\n",(long long) sb.st_size);printf("Blocks allocated:         %lld\n",(long long) sb.st_blocks);printf("Last status change:       %s", ctime(&sb.st_ctime));printf("Last file access:         %s", ctime(&sb.st_atime));printf("Last file modification:   %s", ctime(&sb.st_mtime));exit(EXIT_SUCCESS);
}

读取链接文件

#include <unistd.h>
ssize_t readlink(const char *path, char *buf, size_t bufsiz);

声明：时间有限，目前仅将相关库函数记录下来，后期慢慢完善用法及例程，感兴趣的小伙伴可以先关注，有更新就会提醒哦~