¶ 系统调用(man 2)
- 打开或创建文件
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int open(const char *pathname, int flags);
int open(const char *pathname, int flags, mode_t mode)
int creat(const char *pathname, mode_t mode);
int openat(int dirfd, const char *pathname, int flags);
int openat(int dirfd, const char *pathname, int flags, mode_t mode);- 关闭文件
#include <unistd.h>
int close(int fd);- 创建目录
#include <sys/stat.h>
#include <sys/types.h>
int mkdir(const char *pathname, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
#include <sys/stat.h>
// 在指定目录下创建目录
int mkdirat(int dirfd, const char *pathname, mode_t mode);- 改变工作目录
#include <unistd.h>
int chdir(const char *path);
int fchdir(int fd);- 读取符号连接
符号链接不能直接open+read读取，不然会读取到其指向的文件。
#include <unistd.h>
ssize_t readlink(const char *pathname, char *buf, size_t bufsiz);
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
ssize_t readlinkat(int dirfd, const char *pathname,
char *buf, size_t bufsiz);- 创建符号链接
创建符号链接不能用open+write
#include <unistd.h>
int symlink(const char *target, const char *linkpath);
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
int symlinkat(const char *target, int newdirfd, const char *linkpath);¶ glibc (man 3)
struct dirent {
ino_t d_ino; /* Inode number */
off_t d_off; /* Not an offset; see below */
unsigned short d_reclen; /* Length of this record */
unsigned char d_type; /* Type of file; not supported by all filesystem types */
char d_name[256]; /* Null-terminated filename */
};d_type:
DT_BLK This is a block device.
DT_CHR This is a character device.
DT_DIR This is a directory.
DT_FIFO This is a named pipe (FIFO).
DT_LNK This is a symbolic link.
DT_REG This is a regular file.
DT_SOCK This is a UNIX domain socket.
DT_UNKNOWN The file type could not be determined.- 打开目录
#include <sys/types.h>
#include <dirent.h>
DIR *opendir(const char *name);
DIR *fdopendir(int fd);- 取得目录fd
#include <sys/types.h>
#include <dirent.h>
int dirfd(DIR *dirp);- 遍历目录
#include <dirent.h>
struct dirent *readdir(DIR *dirp);当到达末尾时返回NULL。
- 关闭目录
#include <sys/types.h>
#include <dirent.h>
int closedir(DIR *dirp);- dirname以及basename
#include <libgen.h>
char *dirname(char *path);
char *basename(char *path);一般情况下的规则是先把末尾的/去掉，然后最后一个/后面的就是basename，前面的就是dirname。
特殊情况如下：
If path does not contain a slash, dirname() returns the string "." while basename() returns a copy of path. If path is the string "/", then both dirname() and basename() return the string "/". If path is a null pointer or points to an empty string, then both dirname() and basename() return the string ".".
注意这两个函数可能会修改传进去的字符串。