Linux系统编程之stat函数主要用于获取文件的详细信息,将其结果保存在buf所指向的结构体struct stat中。执行成功则返回0,失败返回-1,错误代码存于errno。
一、 stat函数定义
#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> int stat(const char *pathname, struct stat *statbuf); int fstat(int fd, struct stat *statbuf); int lstat(const char *pathname, struct stat *statbuf); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int fstatat(int dirfd, const char *pathname, struct stat *statbuf, int flags);
二、 struct stat结构体定义
struct stat { dev_t st_dev; /* ID of device containing file */ ino_t st_ino; /* Inode number */ mode_t st_mode; /* File type and mode */ nlink_t st_nlink; /* Number of hard links */ uid_t st_uid; /* User ID of owner */ gid_t st_gid; /* Group ID of owner */ dev_t st_rdev; /* Device ID (if special file) */ off_t st_size; /* Total size, in bytes */ blksize_t st_blksize; /* Block size for filesystem I/O */ blkcnt_t st_blocks; /* Number of 512B blocks allocated */ /* Since Linux 2.6, the kernel supports nanosecond precision for the following timestamp fields. For the details before Linux 2.6, see NOTES. */ struct timespec st_atim; /* Time of last access */ struct timespec st_mtim; /* Time of last modification */ struct timespec st_ctim; /* Time of last status change */ #define st_atime st_atim.tv_sec /* Backward compatibility */ #define st_mtime st_mtim.tv_sec #define st_ctime st_ctim.tv_sec };
三、 测试实例
#include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <stdio.h> #include <stdlib.h> #include <sys/sysmacros.h> int main(void) { struct stat sb; if (stat("statdemo.c", &sb) == -1) { perror("stat error\n"); return EXIT_FAILURE; } printf("ID of containing device: [%lx,%lx]\n", (long) major(sb.st_dev), (long) minor(sb.st_dev)); 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)); return EXIT_SUCCESS; }
四、 运行结果
[ycxie@fedora Workspace]$ gcc statdemo.c -o statdemo [ycxie@fedora Workspace]$ ./statdemo ID of containing device: [fd,0] File type: regular file I-node number: 1442428 Mode: 100644 (octal) Link count: 1 Ownership: UID=1000 GID=1000 Preferred I/O block size: 4096 bytes File size: 1550 bytes Blocks allocated: 8 Last status change: Fri Aug 24 11:24:54 2018 Last file access: Fri Aug 24 11:24:57 2018 Last file modification: Fri Aug 24 11:24:54 2018 [ycxie@fedora Workspace]$ ls -l statdemo.c -rw-r--r-- 1 ycxie ycxie 1550 Aug 24 11:24 statdemo.c